media: imx: capture: Decouple video node from source with MC-centric API

When operating in MC-centric mode, the behaviour of video nodes shall
not be influenced by the active configuration of the source subdev. Add
a set of ioctl handlers that implement this mode, and select them when
support for the legacy API is not requested.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Rui Miguel Silva <rmfrfs@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>