dt-bindings: display: msm: mdp4: add LCDC clock and PLL source

Add the LCDC / LVDS clock input and the XO used to drive internal LVDS
PLL to MDP4 controller bindings. The controller also provides LVDS PHY
PLL, so add optional #clock-cells to the device.

Acked-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/650278/
Link: https://lore.kernel.org/r/20250425-fd-mdp4-lvds-v4-1-6b212160b44c@oss.qualcomm.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>

Documentation/devicetree/bindings/display/msm/mdp4.yaml

@@ -18,9 +18,10 @@ properties:
 
   clocks:
     minItems: 6
-    maxItems: 6
+    maxItems: 8
 
   clock-names:
+    minItems: 6
     items:
       - const: core_clk
       - const: iface_clk
@@ -28,6 +29,12 @@ properties:
       - const: lut_clk
       - const: hdmi_clk
       - const: tv_clk
+      - const: lcdc_clk
+      - const: pxo
+        description: XO used to drive the internal LVDS PLL
+
+  '#clock-cells':
+    const: 0
 
   reg:
     maxItems: 1