media: rcar-vin: Parse parallel input on Gen3

The rcar-vin driver so far had a mutually exclusive code path for
handling parallel and CSI-2 video input subdevices, with only the CSI-2
use case supporting media-controller. As we add support for parallel
inputs to Gen3 media-controller compliant code path now parse both port@0
and port@1, handling the media-controller use case in the parallel
bound/unbind notifier operations.

Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Acked-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>