dt-bindings: can: rcar_can: Document r8a774e1 support

Document SoC specific bindings for RZ/G2H (R8A774E1) SoC.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Marian-Cristian Rotariu <marian-cristian.rotariu.rb@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20201005081319.29322-3-prabhakar.mahadev-lad.rj@bp.renesas.com


Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>