media: mgb4: Add support for YUV image formats

Recent mgb4 firmwares support YUV in addition to the RGB image format.
Enable YUV in the driver when the FW supports it.

Signed-off-by: Martin Tůma <martin.tuma@digiteqautomotive.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>