dt-bindings: soc: qcom: qcom,smd-rpm: add power-controller

Document power-controller child of Qualcomm RPM over SMD to fix
dtbs_check warnings like:

  msm8916-huawei-g7.dtb: rpm-requests: 'power-controller' do not match any of the regexes: 'pinctrl-[0-9]+'
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220504131923.214367-3-krzysztof.kozlowski@linaro.orgSigned-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

Documentation/devicetree/bindings/soc/qcom/qcom,smd-rpm.yaml

@@ -52,6 +52,9 @@ properties:
     $ref: /schemas/clock/qcom,rpmcc.yaml#
     unevaluatedProperties: false
 
+  power-controller:
+    $ref: /schemas/power/qcom,rpmpd.yaml#
+
   qcom,smd-channels:
     $ref: /schemas/types.yaml#/definitions/string-array
     description: Channel name used for the RPM communication