media: sunxi: Add support for the A31 MIPI CSI-2 controller

The A31 MIPI CSI-2 controller is a dedicated MIPI CSI-2 bridge
found on Allwinner SoCs such as the A31 and V3/V3s.

It is a standalone block, connected to the CSI controller on one side
and to the MIPI D-PHY block on the other. It has a dedicated address
space, interrupt line and clock.

It is represented as a V4L2 subdev to the CSI controller and takes a
MIPI CSI-2 sensor as its own subdev, all using the fwnode graph and
media controller API.

Only 8-bit and 10-bit Bayer formats are currently supported.
While up to 4 internal channels to the CSI controller exist, only one
is currently supported by this implementation.

Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Acked-by: Maxime Ripard <mripard@kernel.org>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>