dt-bindings: opp: accept array of frequencies

Devices might need to control several clocks when scaling the frequency
and voltage.  Allow passing array of clock frequencies, similarly to the
voltages.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

Documentation/devicetree/bindings/opp/opp-v2-base.yaml

@@ -50,6 +50,16 @@ patternProperties:
           property to uniquely identify the OPP nodes exists. Devices like power
           domains must have another (implementation dependent) property.
 
+          Entries for multiple clocks shall be provided in the same field, as
+          array of frequencies.  The OPP binding doesn't provide any provisions
+          to relate the values to their clocks or the order in which the clocks
+          need to be configured and that is left for the implementation
+          specific binding.
+        minItems: 1
+        maxItems: 16
+        items:
+          maxItems: 1
+
       opp-microvolt:
         description: |
           Voltage for the OPP