arm64: dts: rockchip: enable HS200 for eMMC on rock64

eMMC that's sold by Pine64 can do HS200, rk3328 can do it
as well, so update DTS to enable it.
Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm64/boot/dts/rockchip/rk3328-rock64.dts

@@ -100,6 +100,7 @@ &cpu3 {
 &emmc {
 	bus-width = <8>;
 	cap-mmc-highspeed;
+	mmc-hs200-1_8v;
 	non-removable;
 	pinctrl-names = "default";
 	pinctrl-0 = <&emmc_clk &emmc_cmd &emmc_bus8>;