arm64: dts: rockchip: enable sdmmc controller on rk3399-firefly

This allows basic support for SD highspeed cards but no UHS-I mode
got ready due to the propagated defer-probe error from RK805.

Cc: Kever Yang <kever.yang@rock-chips.com>
Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm64/boot/dts/rockchip/rk3399-firefly.dts

@@ -630,6 +630,18 @@ &saradc {
 	status = "okay";
 };
 
+&sdmmc {
+	bus-width = <4>;
+	cap-mmc-highspeed;
+	cap-sd-highspeed;
+	cd-gpios = <&gpio0 7 GPIO_ACTIVE_LOW>;
+	disable-wp;
+	max-frequency = <150000000>;
+	pinctrl-names = "default";
+	pinctrl-0 = <&sdmmc_clk &sdmmc_cmd &sdmmc_bus4>;
+	status = "okay";
+};
+
 &sdhci {
 	bus-width = <8>;
 	mmc-hs400-1_8v;