arm64: dts: rockchip: Correct MIPI DPHY PLL clock on rk3399

There is a further gate in between the mipidphy reference clock and the
actual ref-clock input to the dsi host, making the clock hirarchy look like
clk_24m --> Gate11[14] --> clk_mipidphy_ref --> Gate21[0] --> clk_dphy_pll

Fix the clock reference so that the whole clock subtree gets enabled when
the dsi host needs it.
Signed-off-by: Nickey Yang <nickey.yang@rock-chips.com>
[amended commit message]
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

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

@@ -1629,7 +1629,7 @@ mipi_dsi: mipi@ff960000 {
 		compatible = "rockchip,rk3399-mipi-dsi", "snps,dw-mipi-dsi";
 		reg = <0x0 0xff960000 0x0 0x8000>;
 		interrupts = <GIC_SPI 45 IRQ_TYPE_LEVEL_HIGH 0>;
-		clocks = <&cru SCLK_MIPIDPHY_REF>, <&cru PCLK_MIPI_DSI0>,
+		clocks = <&cru SCLK_DPHY_PLL>, <&cru PCLK_MIPI_DSI0>,
 			 <&cru SCLK_DPHY_TX0_CFG>;
 		clock-names = "ref", "pclk", "phy_cfg";
 		power-domains = <&power RK3399_PD_VIO>;