[media] doc-rst: Specify raw bayer format variant used in the examples

The documentation simply mentioned that one of the four pixel orders was
used in the example. Now specify the exact pixelformat instead.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>