drm: rcar-du: lvds: Add support for R8A774E1 SoC

The LVDS encoder on RZ/G2H (R8A774E1) SoC is identical to R-Car Gen3 so
just reuse the rcar_lvds_gen3_info structure to hookup R8A774E1 to LVDS
encoder driver.

Signed-off-by: Marian-Cristian Rotariu <marian-cristian.rotariu.rb@bp.renesas.com>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>