drm: bridge: dw-hdmi: Switch to V4L bus format and encodings

Switch code to use the newly introduced V4L bus formats IDs instead of custom
defines. Also use the V4L encoding defines.

Some display pipelines can only provide non-RBG input pixels to the HDMI TX
Controller, this patch takes the pixel format from the plat_data if provided.

Reviewed-by: Jose Abreu <joabreu@synopsys.com>
Reviewed-by: Archit Taneja <architt@codeaurora.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>