dt-bindings: soc: qcom: qcom,saw2: define optional regulator node

The SAW2 device can optionally provide a voltage regulator supplying the
CPU core, cluster or L2 cache. Change the boolean 'regulator' property
into a proper regulator description. This breaks schema compatibility
for the sake of properly describing the regulator.
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20240102-saw2-spm-regulator-v7-3-0472ec237f49@linaro.orgSigned-off-by: Bjorn Andersson <andersson@kernel.org>

Documentation/devicetree/bindings/soc/qcom/qcom,saw2.yaml

@@ -53,7 +53,7 @@ properties:
     minItems: 1
 
   regulator:
-    type: boolean
+    $ref: /schemas/regulator/regulator.yaml#
     description: Indicates that this SPM device acts as a regulator device
       device for the core (CPU or Cache) the SPM is attached to.
 
@@ -102,4 +102,17 @@ examples:
         reg = <0x17912000 0x1000>;
     };
 
+  - |
+    /*
+     * Example 3: SAW2 with the bundled regulator definition.
+     */
+    power-manager@2089000 {
+        compatible = "qcom,apq8064-saw2-v1.1-cpu", "qcom,saw2";
+        reg = <0x02089000 0x1000>, <0x02009000 0x1000>;
+
+        regulator {
+            regulator-min-microvolt = <850000>;
+            regulator-max-microvolt = <1300000>;
+        };
+    };
 ...