This driver returns an error if unsupported media bus pixel code is
requested by VIDIOC_SUBDEV_S_FMT.

But according to Documentation/media/uapi/v4l/vidioc-subdev-g-fmt.rst,

Drivers must not return an error solely because the requested format
doesn't match the device capabilities. They must instead modify the
format to match what the hardware can provide.

So select default format code and return success in that case.

This is detected by v4l2-compliance.

Cc: "Lad, Prabhakar" <prabhakar.csengg@gmail.com>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>