[media] v4l: ctrls: Add deinterlacing mode control

The menu control selects the operation mode of a video deinterlacer. The
menu entries are driver specific.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran@bingham.xyz>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>