dt-bindings: net: renesas,ether: Document R8A7742 SoC

Document RZ/G1H (R8A7742) SoC bindings.
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: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/net/renesas,ether.yaml

@@ -29,6 +29,7 @@ properties:
               - renesas,rcar-gen1-ether  # a generic R-Car Gen1 device
       - items:
           - enum:
+              - renesas,ether-r8a7742    # device is a part of R8A7742 SoC
               - renesas,ether-r8a7743    # device is a part of R8A7743 SoC
               - renesas,ether-r8a7745    # device is a part of R8A7745 SoC
               - renesas,ether-r8a7790    # device is a part of R8A7790 SoC