dt-bindings: soc: qcom,rpm: add missing clock-controller node

On Qualcomm platforms in addition to regulators the RPM also provides
clocks via the child clock-controller node. Describe it properly in the
schema.

Fixes: 872f91b ("clk: qcom: Add support for RPM Clocks")
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20250318-fix-nexus-4-v2-1-bcedd1406790@oss.qualcomm.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>

Author: lumag

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

@@ -46,6 +46,14 @@ properties:
     description:
       Three entries specifying the outgoing ipc bit used for signaling the RPM.
 
+  clock-controller:
+    type: object
+    additionalProperties: true
+    properties:
+      compatible:
+        contains:
+          const: qcom,rpmcc
+
 patternProperties:
   "^regulators(-[01])?$":
     type: object