media: rcar-vin: Disallow unbinding and binding of individual VINs

media: rcar-vin: Disallow unbinding and binding of individual VINs

The VIN driver have an internal concept of capture groups that covers
multiple instances of the driver. This is handled using the shared media
graph and a single notifier shared between all VIN instances.

This design do not work well if an individual VIN where to be unbound on
its own. The design could be improved up on to allow for this but would
require large changes in the v4l2-async framework. To avoid the
situation suppress the bind and unbind nodes in sysfs.

Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>