media: v4l: Add 1X14 14-bit greyscale media bus code definition

The code is called MEDIA_BUS_FMT_Y14_1X14 and behaves just like
MEDIA_BUS_FMT_Y12_1X12 with two more bits.

Signed-off-by: Daniel Glöckner <dg@emlix.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>