dt-bindings: clock: qcom,gcc-ipq8064: add pll4 to used clocks

On IPQ8064 (and related platforms) the GCC uses PLL4 clock provided by
the LCC clock controller. Mention this in the bindings.

To remain compatible with older bindings, make it optional, as the
driver will fallback to getting the `pll4' clock from the system clocks
list.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20220927113826.246241-2-dmitry.baryshkov@linaro.org

Documentation/devicetree/bindings/clock/qcom,gcc-ipq8064.yaml

@@ -27,14 +27,18 @@ properties:
       - const: syscon
 
   clocks:
+    minItems: 2
     items:
       - description: PXO source
       - description: CXO source
+      - description: PLL4 from LCC
 
   clock-names:
+    minItems: 2
     items:
       - const: pxo
       - const: cxo
+      - const: pll4
 
   thermal-sensor:
     type: object
@@ -51,13 +55,14 @@ unevaluatedProperties: false
 
 examples:
   - |
+    #include <dt-bindings/clock/qcom,lcc-ipq806x.h>
     #include <dt-bindings/interrupt-controller/arm-gic.h>
 
     gcc: clock-controller@900000 {
       compatible = "qcom,gcc-ipq8064", "syscon";
       reg = <0x00900000 0x4000>;
-      clocks = <&pxo_board>, <&cxo_board>;
-      clock-names = "pxo", "cxo";
+      clocks = <&pxo_board>, <&cxo_board>, <&lcc PLL4>;
+      clock-names = "pxo", "cxo", "pll4";
       #clock-cells = <1>;
       #reset-cells = <1>;
       #power-domain-cells = <1>;