[media] pxa_camera: Add remaining Bayer 8 formats

This patch adds Bayer 8 GBRG and RGGB support and move GRBG definition
close to BGGR (so all Bayer 8 variants are together). No other changes are
needed as the driver handles them as RAW data stream.

The RGGB variant was tested in a modified OV9640 driver.

Signed-off-by: Petr Cvek <petr.cvek@tul.cz>
Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>