dt-bindings: ASoC: renesas,rsnd: Add r8a7742 support

Document RZ/G1H (R8A7742) SoC bindings.
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Marian-Cristian Rotariu <marian-cristian.rotariu.rb@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/1590526904-13855-2-git-send-email-prabhakar.mahadev-lad.rj@bp.renesas.comSigned-off-by: Mark Brown <broonie@kernel.org>

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

@@ -263,6 +263,7 @@ Required properties:
 				  "renesas,rcar_sound-gen2" if generation2 (or RZ/G1)
 				  "renesas,rcar_sound-gen3" if generation3 (or RZ/G2)
 				  Examples with soctypes are:
+				    - "renesas,rcar_sound-r8a7742" (RZ/G1H)
 				    - "renesas,rcar_sound-r8a7743" (RZ/G1M)
 				    - "renesas,rcar_sound-r8a7744" (RZ/G1N)
 				    - "renesas,rcar_sound-r8a7745" (RZ/G1E)