arm64: dts: rockchip: add the grf clk for dw-mipi-dsi on rk3399

The clk of grf must be enabled before writing grf
register for rk3399.
Signed-off-by: Nickey Yang <nickey.yang@rock-chips.com>
[the grf clock is already part of the binding since march 2017]
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

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

@@ -1630,8 +1630,8 @@ mipi_dsi: mipi@ff960000 {
 		reg = <0x0 0xff960000 0x0 0x8000>;
 		interrupts = <GIC_SPI 45 IRQ_TYPE_LEVEL_HIGH 0>;
 		clocks = <&cru SCLK_DPHY_PLL>, <&cru PCLK_MIPI_DSI0>,
-			 <&cru SCLK_DPHY_TX0_CFG>;
-		clock-names = "ref", "pclk", "phy_cfg";
+			 <&cru SCLK_DPHY_TX0_CFG>, <&cru PCLK_VIO_GRF>;
+		clock-names = "ref", "pclk", "phy_cfg", "grf";
 		power-domains = <&power RK3399_PD_VIO>;
 		rockchip,grf = <&grf>;
 		status = "disabled";