media: imx: utils: fix and simplify pixel format enumeration

Merge yuv_formats and rgb_formats into a single array. Always loop over
all entries, skipping those that do not match the requested search
criteria. This simplifies the code, lets us get rid of the manual
counting of array entries, and stops accidentally ignoring some non-mbus
RGB formats.

Before:

  $ v4l2-ctl -d /dev/video14 --list-formats-out
  ioctl: VIDIOC_ENUM_FMT
	Type: Video Output

	[0]: 'UYVY' (UYVY 4:2:2)
	[1]: 'YUYV' (YUYV 4:2:2)
	[2]: 'YU12' (Planar YUV 4:2:0)
	[3]: 'YV12' (Planar YVU 4:2:0)
	[4]: '422P' (Planar YUV 4:2:2)
	[5]: 'NV12' (Y/CbCr 4:2:0)
	[6]: 'NV16' (Y/CbCr 4:2:2)
	[7]: 'RGBP' (16-bit RGB 5-6-5)
	[8]: 'RGB3' (24-bit RGB 8-8-8)
	[9]: 'BX24' (32-bit XRGB 8-8-8-8)

After:

  $ v4l2-ctl -d /dev/video14 --list-formats-out
  ioctl: VIDIOC_ENUM_FMT
	Type: Video Output

	[0]: 'UYVY' (UYVY 4:2:2)
	[1]: 'YUYV' (YUYV 4:2:2)
	[2]: 'YU12' (Planar YUV 4:2:0)
	[3]: 'YV12' (Planar YVU 4:2:0)
	[4]: '422P' (Planar YUV 4:2:2)
	[5]: 'NV12' (Y/CbCr 4:2:0)
	[6]: 'NV16' (Y/CbCr 4:2:2)
	[7]: 'RGBP' (16-bit RGB 5-6-5)
	[8]: 'RGB3' (24-bit RGB 8-8-8)
	[9]: 'BGR3' (24-bit BGR 8-8-8)
	[10]: 'BX24' (32-bit XRGB 8-8-8-8)
	[11]: 'XR24' (32-bit BGRX 8-8-8-8)
	[12]: 'RX24' (32-bit XBGR 8-8-8-8)
	[13]: 'XB24' (32-bit RGBX 8-8-8-8)

Tested on a imx6q-sabresd.

[laurent.pinchart@ideasonboard.com: Make loop counters unsigned]
[laurent.pinchart@ideasonboard.com: Decrement index instead of adding a counter]
[laurent.pinchart@ideasonboard.com: Return directly from within loop instead of breaking]
[slongerbeam@gmail.com: Fix colorspace comparison error]

Fixes: e1302912 ("[media] media: Add i.MX media core driver")
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Tested-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Steve Longerbeam <slongerbeam@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>