dt-bindings: gpio: rcar: Document r8a77961 support

Document support for the GPIO controller in the Renesas R-Car M3-W+
(R8A77961) SoC.

Update all references to R-Car M3-W from "r8a7796" to "r8a77960", to
avoid confusion between R-Car M3-W (R8A77960) and M3-W+.

No driver update is needed.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20191205133912.6048-1-geert+renesas@glider.beSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

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

@@ -18,7 +18,8 @@ Required Properties:
     - "renesas,gpio-r8a7793": for R8A7793 (R-Car M2-N) compatible GPIO controller.
     - "renesas,gpio-r8a7794": for R8A7794 (R-Car E2) compatible GPIO controller.
     - "renesas,gpio-r8a7795": for R8A7795 (R-Car H3) compatible GPIO controller.
-    - "renesas,gpio-r8a7796": for R8A7796 (R-Car M3-W) compatible GPIO controller.
+    - "renesas,gpio-r8a7796": for R8A77960 (R-Car M3-W) compatible GPIO controller.
+    - "renesas,gpio-r8a77961": for R8A77961 (R-Car M3-W+) compatible GPIO controller.
     - "renesas,gpio-r8a77965": for R8A77965 (R-Car M3-N) compatible GPIO controller.
     - "renesas,gpio-r8a77970": for R8A77970 (R-Car V3M) compatible GPIO controller.
     - "renesas,gpio-r8a77980": for R8A77980 (R-Car V3H) compatible GPIO controller.