[media] rcar-vin: add dependency on MEDIA_CONTROLLER

This is done in preparation for Gen3 support where media controller
support will be mandatory for the driver.

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