dt-bindings: arm/cpus: Allow 2 power-domains entries

Some platforms have both "perf" and "psci" power domains, so allow 2
entries.

Signed-off-by: Rob Herring (Arm) <robh@kernel.org>

Documentation/devicetree/bindings/arm/cpus.yaml

@@ -313,7 +313,8 @@ properties:
     maxItems: 1
 
   power-domains:
-    maxItems: 1
+    minItems: 1
+    maxItems: 2
 
   power-domain-names:
     description:
@@ -321,7 +322,10 @@ properties:
       PM domain provider, must be "psci". For SCMI based platforms, the name
       corresponding to the index of an SCMI performance domain provider, must be
       "perf".
-    enum: [ psci, perf, cpr ]
+    minItems: 1
+    maxItems: 2
+    items:
+      enum: [ psci, perf, cpr ]
 
   resets:
     maxItems: 1