media: v4l: Add packed Bayer raw12 pixel formats

These formats are compressed 12-bit raw bayer formats with four different
pixel orders. They are similar to 10-bit variants. The formats added by
this patch are

	V4L2_PIX_FMT_SBGGR12P
	V4L2_PIX_FMT_SGBRG12P
	V4L2_PIX_FMT_SGRBG12P
	V4L2_PIX_FMT_SRGGB12P

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>