[media] rcar-vin: move functions which acts on hardware

This only moves whole structs, defines and functions around, no code is
changed inside any function. The reason for moving this code around is
to prepare for refactoring and fixing of a start/stop stream bug without
having to use forward declarations.

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>