arm64: dts: renesas: r8a774e1-hihope-rzg2h: Enable HS400 mode

This patch enables HS400 mode on HiHope RZ/G2H board.
Signed-off-by: Biju Das <biju.das@bp.renesas.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lore.kernel.org/r/20200819080841.3475-1-biju.das.jz@bp.renesas.comSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

arch/arm64/boot/dts/renesas/r8a774e1-hihope-rzg2h.dts

@@ -35,3 +35,7 @@ &du {
 	clock-names = "du.0", "du.1", "du.3",
 		      "dclkin.0", "dclkin.1", "dclkin.3";
 };
+
+&sdhi3 {
+	mmc-hs400-1_8v;
+};