media: atomisp: add NULL check for asd obtained from atomisp_video_pipe

This is almost a BUG report with RFC patch that just avoids kernel
oopses. Thus, prefixed with [BUG][RFC].

Here is the kernel log after running `v4l2-compliance -d /dev/video4`
with this patch applied:

	kern  :err   : [25507.580392] atomisp-isp2 0000:00:03.0: can't change power state from D3cold to D0 (config space inaccessible)
	kern  :warn  : [25507.592343] isys dma store at addr(0xcd408) val(0)
	kern  :err   : [25507.592995] atomisp-isp2 0000:00:03.0: atomisp_queryctl(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.593685] atomisp-isp2 0000:00:03.0: atomisp_g_input(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.593719] atomisp-isp2 0000:00:03.0: atomisp_g_parm(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.593727] atomisp-isp2 0000:00:03.0: atomisp_queryctl(): asd is NULL, device is ATOMISP ISP ACC
	[omitting 42 same messages]
	kern  :err   : [25507.593976] atomisp-isp2 0000:00:03.0: atomisp_queryctl(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.594191] atomisp-isp2 0000:00:03.0: atomisp_g_input(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.594449] atomisp-isp2 0000:00:03.0: atomisp_queryctl(): asd is NULL, device is ATOMISP ISP ACC
	[omitting 43 same messages]
	kern  :err   : [25507.594756] atomisp-isp2 0000:00:03.0: atomisp_queryctl(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.594779] atomisp-isp2 0000:00:03.0: atomisp_g_ctrl(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.594787] atomisp-isp2 0000:00:03.0: atomisp_s_ctrl(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.594803] atomisp-isp2 0000:00:03.0: atomisp_camera_g_ext_ctrls(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.594880] atomisp-isp2 0000:00:03.0: atomisp_enum_fmt_cap(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.594915] atomisp-isp2 0000:00:03.0: atomisp_g_parm(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.595058] atomisp-isp2 0000:00:03.0: atomisp_try_fmt(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.595089] atomisp-isp2 0000:00:03.0: atomisp_set_fmt(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.595124] atomisp-isp2 0000:00:03.0: atomisp_set_fmt(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.595221] atomisp-isp2 0000:00:03.0: atomisp_set_fmt(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.595241] atomisp-isp2 0000:00:03.0: atomisp_set_fmt(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.601571] atomisp-isp2 0000:00:03.0: can't change power state from D3cold to D0 (config space inaccessible)
	kern  :warn  : [25507.607496] isys dma store at addr(0xcd408) val(0)
	kern  :err   : [25507.608604] atomisp-isp2 0000:00:03.0: atomisp_queryctl(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.611988] atomisp-isp2 0000:00:03.0: can't change power state from D3cold to D0 (config space inaccessible)
	kern  :warn  : [25507.617420] isys dma store at addr(0xcd408) val(0)
	kern  :err   : [25507.618429] atomisp-isp2 0000:00:03.0: atomisp_queryctl(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.618811] atomisp-isp2 0000:00:03.0: atomisp_g_parm(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.622193] atomisp-isp2 0000:00:03.0: can't change power state from D3cold to D0 (config space inaccessible)
	kern  :warn  : [25507.627355] isys dma store at addr(0xcd408) val(0)
	kern  :err   : [25507.628391] atomisp-isp2 0000:00:03.0: atomisp_queryctl(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.631143] atomisp-isp2 0000:00:03.0: can't change power state from D3cold to D0 (config space inaccessible)
	kern  :warn  : [25507.635813] isys dma store at addr(0xcd408) val(0)
	kern  :err   : [25507.636489] atomisp-isp2 0000:00:03.0: atomisp_queryctl(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.636504] atomisp-isp2 0000:00:03.0: atomisp_s_input(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.636516] atomisp-isp2 0000:00:03.0: atomisp_set_fmt(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.639111] atomisp-isp2 0000:00:03.0: can't change power state from D3cold to D0 (config space inaccessible)
	kern  :warn  : [25507.646152] isys dma store at addr(0xcd408) val(0)
	kern  :err   : [25507.646831] atomisp-isp2 0000:00:03.0: atomisp_queryctl(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.646847] atomisp-isp2 0000:00:03.0: atomisp_s_input(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.650079] atomisp-isp2 0000:00:03.0: can't change power state from D3cold to D0 (config space inaccessible)
	kern  :warn  : [25507.657476] isys dma store at addr(0xcd408) val(0)
	kern  :err   : [25507.658741] atomisp-isp2 0000:00:03.0: atomisp_queryctl(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.658759] atomisp-isp2 0000:00:03.0: atomisp_s_input(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.658771] atomisp-isp2 0000:00:03.0: atomisp_set_fmt(): asd is NULL, device is ATOMISP ISP ACC
	kern  :err   : [25507.660959] atomisp-isp2 0000:00:03.0: can't change power state from D3cold to D0 (config space inaccessible)
	kern  :warn  : [25507.666665] isys dma store at addr(0xcd408) val(0)
	kern  :err   : [25507.667397] atomisp-isp2 0000:00:03.0: atomisp_queryctl(): asd is NULL, device is ATOMISP ISP ACC

[mchehab: fix coding style]
Signed-off-by: Tsuchiya Yuto <kitakar@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>