[media] media/vivid: Add support for Y16 format

Support for V4L2_PIX_FMT_Y16, a 16 bit greyscale format.

Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>