dt-bindings: pinctrl: renesas,pfc: Document r8a779f0 support

Document Pin Function Controller (PFC) support for the Renesas R-Car
S4-8 (R8A779F0) SoC.
Signed-off-by: LUU HOAI <hoai.luu.ub@renesas.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Link: https://lore.kernel.org/r/d51828853396773be2d6837f3301ac9da8b6f29e.1645457792.git.geert+renesas@glider.be

Documentation/devicetree/bindings/pinctrl/renesas,pfc.yaml

@@ -44,6 +44,7 @@ properties:
       - renesas,pfc-r8a77990    # R-Car E3
       - renesas,pfc-r8a77995    # R-Car D3
       - renesas,pfc-r8a779a0    # R-Car V3U
+      - renesas,pfc-r8a779f0    # R-Car S4-8
       - renesas,pfc-sh73a0      # SH-Mobile AG5
 
   reg: