media: dt-bindings: alvium: add document YAML binding

media: dt-bindings: alvium: add document YAML binding

Add documentation of device tree in YAML schema for the ALVIUM
Camera from Allied Vision Inc.

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

Signed-off-by: Tommaso Merciai <tomm.merciai@gmail.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>