media: i2c: Add support for alvium camera

The Alvium camera is shipped with sensor + isp in the same housing.
The camera can be equipped with one out of various sensor and abstract
the user from this. Camera is connected via MIPI CSI-2.

Most of the camera module features are supported, with the main exception
being fw update.

The driver provides all mandatory, optional and recommended V4L2 controls
for maximum compatibility with libcamera

References:
 - https://www.alliedvision.com/en/products/embedded-vision-solutions



Signed-off-by: Tommaso Merciai <tomm.merciai@gmail.com>
[Sakari Ailus: Assign ret before using it in probe and squash Tommaso's
	       other fixes.]
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
[hverkuil: alvium-csi2.h: SPDX must use /* */ instead of //]