dt-bindings: perf: arm-cmn: Add CI-700

CI-700 is a new client-level coherent interconnect derived from
the enterprise-level CMN family, and shares the same PMU design.

CC: devicetree@vger.kernel.org
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/5f0b372f808f1468e6d9500cedafbecd10254674.1638530442.git.robin.murphy@arm.comSigned-off-by: Will Deacon <will@kernel.org>

Documentation/devicetree/bindings/perf/arm,cmn.yaml

@@ -12,12 +12,14 @@ maintainers:
 
 properties:
   compatible:
-    const: arm,cmn-600
+    enum:
+      - arm,cmn-600
+      - arm,ci-700
 
   reg:
     items:
       - description: Physical address of the base (PERIPHBASE) and
-          size (up to 64MB) of the configuration address space.
+          size of the configuration address space.
 
   interrupts:
     minItems: 1
@@ -31,13 +33,22 @@ properties:
 
   arm,root-node:
     $ref: /schemas/types.yaml#/definitions/uint32
-    description: Offset from PERIPHBASE of the configuration
-      discovery node (see TRM definition of ROOTNODEBASE).
+    description: Offset from PERIPHBASE of CMN-600's configuration
+      discovery node (see TRM definition of ROOTNODEBASE). Not
+      relevant for newer CMN/CI products.
 
 required:
   - compatible
   - reg
   - interrupts
+
+if:
+  properties:
+    compatible:
+      contains:
+        const: arm,cmn-600
+then:
+  required:
     - arm,root-node
 
 additionalProperties: false