[media] v4l2: replace enum_mbus_fmt by enum_mbus_code

Replace all calls to the enum_mbus_fmt video op by the pad
enum_mbus_code op and remove the duplicate video op.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: Scott Jiang <scott.jiang.linux@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kamil Debski <k.debski@samsung.com>
Acked-by: Prabhakar Lad <prabhakar.csengg@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>