[media] media: imx: Add Capture Device Interface

This is the capture device interface driver that provides the v4l2
user interface. Frames can be received from various sources:

- directly from CSI for capturing unconverted images directly from
  camera sensors.

- from the IC pre-process encode task.

- from the IC pre-process viewfinder task.

Signed-off-by: Steve Longerbeam <steve_longerbeam@mentor.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>