dt-bindings: power: renesas,rcar-sysc: Document R-Car V4M support

Document support for the System Controller (SYSC) in the R-Car V4M
(R8A779H0) SoC.
Signed-off-by: Duy Nguyen <duy.nguyen.rh@renesas.com>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/6315cbd0b6e9b92a7914d98f397a2c663ad521c6.1706194617.git.geert+renesas@glider.beSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Documentation/devicetree/bindings/power/renesas,rcar-sysc.yaml

@@ -45,6 +45,7 @@ properties:
       - renesas,r8a779a0-sysc # R-Car V3U
       - renesas,r8a779f0-sysc # R-Car S4-8
       - renesas,r8a779g0-sysc # R-Car V4H
+      - renesas,r8a779h0-sysc # R-Car V4M
 
   reg:
     maxItems: 1