dt-bindings: gpio: renesas,rcar-gpio: Add r8a779f0 support

Document support for the GPIO controller blocks in the Renesas R-Car
S4-8 (R8A779F0) SoC, including a new family-specific compatible value
for the R-Car Gen4 family.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>

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

@@ -51,6 +51,11 @@ properties:
       - items:
           - const: renesas,gpio-r8a779a0  # R-Car V3U
 
+      - items:
+          - enum:
+              - renesas,gpio-r8a779f0     # R-Car S4-8
+          - const: renesas,rcar-gen4-gpio # R-Car Gen4
+
   reg:
     maxItems: 1