arm64: dts: renesas: enable HS400 on R-Car Gen3

Successfully tested on H3 ES2.0 and M3-N ES1.0.
Transfer rates where >160MB/s for H3 and >200MB/s for M3-N.
Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm64/boot/dts/renesas/salvator-common.dtsi

@@ -764,6 +764,7 @@ &sdhi2 {
 	vqmmc-supply = <&reg_1p8v>;
 	bus-width = <8>;
 	mmc-hs200-1_8v;
+	mmc-hs400-1_8v;
 	non-removable;
 	fixed-emmc-driver-type = <1>;
 	status = "okay";

arch/arm64/boot/dts/renesas/ulcb.dtsi

@@ -463,6 +463,7 @@ &sdhi2 {
 	vqmmc-supply = <&reg_1p8v>;
 	bus-width = <8>;
 	mmc-hs200-1_8v;
+	mmc-hs400-1_8v;
 	non-removable;
 	status = "okay";
 };