dt-bindings: firmware: qcom,scm: Add optional interrupt

Add an interrupt specification to the bindings to support the wait-queue
feature on SM8450 SoCs.

Signed-off-by: Guru Das Srinagesh <quic_gurus@quicinc.com>
Signed-off-by: Sibi Sankar <quic_sibis@quicinc.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230113161114.22607-2-quic_sibis@quicinc.com

Documentation/devicetree/bindings/firmware/qcom,scm.yaml

@@ -74,6 +74,12 @@ properties:
   '#reset-cells':
     const: 1
 
+  interrupts:
+    description:
+      The wait-queue interrupt that firmware raises as part of handshake
+      protocol to handle sleeping SCM calls.
+    maxItems: 1
+
   qcom,dload-mode:
     $ref: /schemas/types.yaml#/definitions/phandle-array
     items:
@@ -163,6 +169,18 @@ allOf:
       properties:
         interconnects: false
 
+  # Interrupts
+  - if:
+      not:
+        properties:
+          compatible:
+            contains:
+              enum:
+                - qcom,scm-sm8450
+    then:
+      properties:
+        interrupts: false
+
 required:
   - compatible