Convert video-interfaces.txt to DT schema. As it contains a mixture of
device level and endpoint properties, split it up into 2 schemas.

Binding schemas will need to reference both the graph.yaml and
video-interfaces.yaml schemas. The exact schema depends on how many
ports and endpoints for the binding. A single port with a single
endpoint looks similar to this:

  port:
    $ref: /schemas/graph.yaml#/$defs/port-base

    properties:
      endpoint:
        $ref: video-interfaces.yaml#
        unevaluatedProperties: false

        properties:
          bus-width:
            enum: [ 8, 10, 12, 16 ]

          pclk-sample: true
          hsync-active: true
          vsync-active: true

        required:
          - bus-width

    additionalProperties: false
Acked-by: NSakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: NJacopo Mondi <jacopo@jmondi.org>
Acked-by: NGuennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: NHans Verkuil <hverkuil-cisco@xs4all.nl>
Reviewed-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NRob Herring <robh@kernel.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab+huawei@kernel.org>