arm64: dts: qcom: msm8996: add missing DSI clock assignments

Add missing DSI clock assignments to properly use DSI PHY clocks as DSI
byte and pixel clock parents.
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220706145412.1566011-1-dmitry.baryshkov@linaro.org

arch/arm64/boot/dts/qcom/msm8996.dtsi

@@ -981,6 +981,8 @@ dsi0: dsi@994000 {
 					      "core_mmss",
 					      "pixel",
 					      "core";
+				assigned-clocks = <&mmcc BYTE0_CLK_SRC>, <&mmcc PCLK0_CLK_SRC>;
+				assigned-clock-parents = <&dsi0_phy 0>, <&dsi0_phy 1>;
 
 				phys = <&dsi0_phy>;
 				phy-names = "dsi";
@@ -1047,6 +1049,8 @@ dsi1: dsi@996000 {
 					      "core_mmss",
 					      "pixel",
 					      "core";
+				assigned-clocks = <&mmcc BYTE1_CLK_SRC>, <&mmcc PCLK1_CLK_SRC>;
+				assigned-clock-parents = <&dsi1_phy 0>, <&dsi1_phy 1>;
 
 				phys = <&dsi1_phy>;
 				phy-names = "dsi";