Describe HDMI input connector and ADV7612 HDMI decoder installed on
R-Car Gen3 Draak board.

The video signal routing to the HDMI decoder to the video input interface
VIN4 is multiplexed with CVBS input path, and enabled/disabled through
on-board switches SW-49, SW-50, SW-51 and SW-52.

As the default board switches configuration connects CVBS input to VIN4,
leave the HDMI decoder unconnected in DTS.
Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>