dt-bindings: riscv: sifive-l2: add a PolarFire SoC compatible

The l2 cache on PolarFire SoC is cross between that of the fu540 and
the fu740. It has the extra interrupt from the fu740 but the lower
number of cache-sets. Add a specific compatible to avoid the likes
of:

mpfs-polarberry.dtb: cache-controller@2010000: interrupts: [[1], [3], [4], [2]] is too long

Fixes: 34fc9cc3ae ("riscv: dts: microchip: correct L2 cache interrupts")
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>

Documentation/devicetree/bindings/riscv/sifive-l2-cache.yaml

@@ -17,9 +17,6 @@ description:
   acts as directory-based coherency manager.
   All the properties in ePAPR/DeviceTree specification applies for this platform.
 
-allOf:
-  - $ref: /schemas/cache-controller.yaml#
-
 select:
   properties:
     compatible:
@@ -33,11 +30,16 @@ select:
 
 properties:
   compatible:
-    items:
-      - enum:
-          - sifive,fu540-c000-ccache
-          - sifive,fu740-c000-ccache
-      - const: cache
+    oneOf:
+      - items:
+          - enum:
+              - sifive,fu540-c000-ccache
+              - sifive,fu740-c000-ccache
+          - const: cache
+      - items:
+          - const: microchip,mpfs-ccache
+          - const: sifive,fu540-c000-ccache
+          - const: cache
 
   cache-block-size:
     const: 64
@@ -72,29 +74,46 @@ properties:
       The reference to the reserved-memory for the L2 Loosely Integrated Memory region.
       The reserved memory node should be defined as per the bindings in reserved-memory.txt.
 
-if:
-  properties:
-    compatible:
-      contains:
-        const: sifive,fu540-c000-ccache
+allOf:
+  - $ref: /schemas/cache-controller.yaml#
 
-then:
-  properties:
-    interrupts:
-      description: |
-        Must contain entries for DirError, DataError and DataFail signals.
-      maxItems: 3
-    cache-sets:
-      const: 1024
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - sifive,fu740-c000-ccache
+              - microchip,mpfs-ccache
 
-else:
-  properties:
-    interrupts:
-      description: |
-        Must contain entries for DirError, DataError, DataFail, DirFail signals.
-      minItems: 4
-    cache-sets:
-      const: 2048
+    then:
+      properties:
+        interrupts:
+          description: |
+            Must contain entries for DirError, DataError, DataFail, DirFail signals.
+          minItems: 4
+
+    else:
+      properties:
+        interrupts:
+          description: |
+            Must contain entries for DirError, DataError and DataFail signals.
+          maxItems: 3
+
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: sifive,fu740-c000-ccache
+
+    then:
+      properties:
+        cache-sets:
+          const: 2048
+
+    else:
+      properties:
+        cache-sets:
+          const: 1024
 
 additionalProperties: false