[media] V4L: replace soc-camera specific soc_mediabus.h with v4l2-mediabus.h

Most users of the <media/soc_mediabus.h> header only need pixel code
definitions, which are now located in the generic <linux/v4l2-mediabus.h>
header. Switch over to reduce soc-camera dependencies.

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