media: dt-bindings: media: renesas,drif: Add r8a77965 support

The r8a77965 (a.k.a. R-Car M3-N) device tree schema is
compatible with the already documented R-Car Gen3 devices.

Document r8a77965 support within renesas,drif.yaml.

Signed-off-by: Fabrizio Castro <fabrizio.castro.jz@renesas.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>