media: platform: fix VIA_CAMERA dependencies

As detected by a randconfig:

	WARNING: unmet direct dependencies detected for VIDEO_OV7670
	  Depends on [n]: MEDIA_SUPPORT [=y] && I2C [=y] && VIDEO_V4L2 [=n]
	  Selected by [y]:
	  - VIDEO_VIA_CAMERA [=y] && MEDIA_SUPPORT [=y] && MEDIA_PLATFORM_SUPPORT [=y] && V4L_PLATFORM_DRIVERS [=y] && FB_VIA [=y]

There's a missing dependency on VIDEO_V4L2 for VIA_CAMERA.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>