dt-bindings: gpio: rcar: Add r8a77470 (RZ/G1C) support

Renesas RZ/G1C (R8A77470) SoC GPIO blocks are identical to the R-Car Gen2
family. Add support for its GPIO controllers.
Signed-off-by: Biju Das <biju.das@bp.renesas.com>
Reviewed-by: Chris Paterson <chris.paterson2@renesas.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Documentation/devicetree/bindings/gpio/renesas,gpio-rcar.txt

@@ -5,6 +5,7 @@ Required Properties:
   - compatible: should contain one or more of the following:
     - "renesas,gpio-r8a7743": for R8A7743 (RZ/G1M) compatible GPIO controller.
     - "renesas,gpio-r8a7745": for R8A7745 (RZ/G1E) compatible GPIO controller.
+    - "renesas,gpio-r8a77470": for R8A77470 (RZ/G1C) compatible GPIO controller.
     - "renesas,gpio-r8a7778": for R8A7778 (R-Car M1) compatible GPIO controller.
     - "renesas,gpio-r8a7779": for R8A7779 (R-Car H1) compatible GPIO controller.
     - "renesas,gpio-r8a7790": for R8A7790 (R-Car H2) compatible GPIO controller.