[media] V4L: mt9m001, mt9v022: use internally cached pixel code

Using the internally cached pixel code, instead of the one, provided by
the soc-camera, removes one more use of struct soc_camera_device in these
drivers. Also remove the no longer needed soc_camera_from_i2c() inline
function.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>