dt-bindings: pinctrl: renesas,pfc: Document R-Car V4M support

Document support for the Pin Function Controller (PFC) in the Renesas
R-Car V4M (R8A779H0) SoC.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/56685dc04af3cee7cb3751e855ed5b3679b14122.1706264667.git.geert+renesas@glider.be

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

@@ -46,6 +46,7 @@ properties:
       - renesas,pfc-r8a779a0    # R-Car V3U
       - renesas,pfc-r8a779f0    # R-Car S4-8
       - renesas,pfc-r8a779g0    # R-Car V4H
+      - renesas,pfc-r8a779h0    # R-Car V4M
       - renesas,pfc-sh73a0      # SH-Mobile AG5
 
   reg: