media: rcar-vin: use different v4l2 operations in media controller mode

When the driver runs in media controller mode it should not directly
control the subdevice instead userspace will be responsible for
configuring the pipeline. To be able to run in this mode a different set
of v4l2 operations needs to be used.

Add a new set of v4l2 operations to support operation without directly
interacting with the source subdevice.

Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>