arm64: dts: renesas: r8a779a0: Add DSI encoders

Provide the two MIPI DSI encoders on the V3U and connect them to the DU
accordingly.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Link: https://lore.kernel.org/r/20211130164311.2909616-2-kieran.bingham+renesas@ideasonboard.com


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>