dt-bindings: serial: renesas, hscif: Document r8a774e1 bindings

RZ/G2H (R8A774E1) SoC also has the R-Car gen3 compatible HSCIF ports,
so document the SoC specific bindings.
Reviewed-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NLad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lore.kernel.org/r/1594230511-24790-3-git-send-email-prabhakar.mahadev-lad.rj@bp.renesas.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/serial/renesas,hscif.yaml

@@ -42,6 +42,7 @@ properties:
               - renesas,hscif-r8a774a1     # RZ/G2M
               - renesas,hscif-r8a774b1     # RZ/G2N
               - renesas,hscif-r8a774c0     # RZ/G2E
+              - renesas,hscif-r8a774e1     # RZ/G2H
               - renesas,hscif-r8a7795      # R-Car H3
               - renesas,hscif-r8a7796      # R-Car M3-W
               - renesas,hscif-r8a77961     # R-Car M3-W+