media: rcar-vin: add chsel information to rvin_info

Each Gen3 SoC has a limited set of predefined routing possibilities for
which CSI-2 device and channel can be routed to which VIN instance.
Prepare to store this information in the struct rvin_info.

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>