ASoC: renesas,rsnd: Add r8a77961 support

Document R-Car M3-W+ (R8A77961) SoC bindings.
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/87a6vwbavq.wl-kuninori.morimoto.gx@renesas.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/renesas,rsnd.yaml

@@ -43,6 +43,7 @@ properties:
               - renesas,rcar_sound-r8a774e1  # RZ/G2H
               - renesas,rcar_sound-r8a7795   # R-Car H3
               - renesas,rcar_sound-r8a7796   # R-Car M3-W
+              - renesas,rcar_sound-r8a77961  # R-Car M3-W+
               - renesas,rcar_sound-r8a77965  # R-Car M3-N
               - renesas,rcar_sound-r8a77990  # R-Car E3
               - renesas,rcar_sound-r8a77995  # R-Car D3