dt-bindings: Add binding information for llcc_perfmon

Add LLCC perfmon child node entry in documentation.

Change-Id: If006d1203c0d6fed639285f9e5bea4903873b7ed
Signed-off-by: Aman Kanwar <quic_akanwar@quicinc.com>

bindings/arm/msm/qcom,llcc.yaml

@@ -46,6 +46,12 @@ properties:
   interrupts:
     maxItems: 1
 
+  child-node:
+    description: Container of llcc_perfmon node
+    type: object
+    properties:
+        compatible:
+            const: qcom,llcc-perfmon
 required:
   - compatible
   - reg
@@ -94,5 +100,9 @@ examples:
             reg-names = "llcc0_base", "llcc1_base", "llcc2_base",
                 "llcc3_base", "llcc_broadcast_base";
             interrupts = <GIC_SPI 582 IRQ_TYPE_LEVEL_HIGH>;
+
+            llcc_perfmon {
+                compatible = "qcom,llcc-perfmon";
+            }
         };
     };