mmc: renesas_sdhi: Add r8a774a1 support

Document RZ/G2M (R8A774A1) SoC bindings.
Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Reviewed-by: Biju Das <biju.das@bp.renesas.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Documentation/devicetree/bindings/mmc/tmio_mmc.txt

@@ -17,6 +17,7 @@ Required properties:
 		"renesas,sdhi-r8a7740" - SDHI IP on R8A7740 SoC
 		"renesas,sdhi-r8a7743" - SDHI IP on R8A7743 SoC
 		"renesas,sdhi-r8a7745" - SDHI IP on R8A7745 SoC
+		"renesas,sdhi-r8a774a1" - SDHI IP on R8A774A1 SoC
 		"renesas,sdhi-r8a7778" - SDHI IP on R8A7778 SoC
 		"renesas,sdhi-r8a7779" - SDHI IP on R8A7779 SoC
 		"renesas,sdhi-r8a7790" - SDHI IP on R8A7790 SoC
@@ -34,7 +35,8 @@ Required properties:
 		"renesas,rcar-gen1-sdhi" - a generic R-Car Gen1 SDHI controller
 		"renesas,rcar-gen2-sdhi" - a generic R-Car Gen2 or RZ/G1
 					   SDHI controller
-		"renesas,rcar-gen3-sdhi" - a generic R-Car Gen3 SDHI controller
+		"renesas,rcar-gen3-sdhi" - a generic R-Car Gen3 or RZ/G2
+					   SDHI controller
 
 
 		When compatible with the generic version, nodes must list