media: dt-bindings: video-interfaces: add video-interfaces.h information

media: dt-bindings: video-interfaces: add video-interfaces.h information

Mention include/dt-bindings/media/video-interfaces.h in descriptions to
help avoid use hardcode in dts.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>