arm64: dts: rockchip: make rk3399's grf a "simple-mfd"

Per the examples in
Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt, we need the
grf node to be a simple-mfd in order to properly enumerate child devices
like our eMMC PHY.
Signed-off-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>

[directly mimic for the pmugrf, which will need the same change later
and there is no need to pollute commit history with another patch]
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm64/boot/dts/rockchip/rk3399.dtsi

@@ -390,8 +390,10 @@ spi5: spi@ff200000 {
 	};
 
 	pmugrf: syscon@ff320000 {
-		compatible = "rockchip,rk3399-pmugrf", "syscon";
+		compatible = "rockchip,rk3399-pmugrf", "syscon", "simple-mfd";
 		reg = <0x0 0xff320000 0x0 0x1000>;
+		#address-cells = <1>;
+		#size-cells = <1>;
 	};
 
 	spi3: spi@ff350000 {
@@ -497,8 +499,10 @@ cru: clock-controller@ff760000 {
 	};
 
 	grf: syscon@ff770000 {
-		compatible = "rockchip,rk3399-grf", "syscon";
+		compatible = "rockchip,rk3399-grf", "syscon", "simple-mfd";
 		reg = <0x0 0xff770000 0x0 0x10000>;
+		#address-cells = <1>;
+		#size-cells = <1>;
 	};
 
 	watchdog@ff840000 {