media: i2c: imx219: Add support for RAW8 bit bayer format

IMX219 sensor is capable for RAW8/RAW10 modes. This commit adds support
for RAW8 bayer format.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>