dt-bindings: riscv: cpus: add ref to interrupt-controller

removed the redundant properties for interrupt-controller
and provide reference to the riscv,cpu-intc.yaml which defines
the interrupt-controller. making the properties for riscv
interrupt-controller at a central place.
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Kanak Shilledar <kanakshilledar@gmail.com>
Link: https://lore.kernel.org/r/20240615021507.122035-3-kanakshilledar@gmail.comSigned-off-by: Palmer Dabbelt <palmer@rivosinc.com>

Documentation/devicetree/bindings/riscv/cpus.yaml

@@ -102,26 +102,7 @@ properties:
 
   interrupt-controller:
     type: object
-    additionalProperties: false
-    description: Describes the CPU's local interrupt controller
-
-    properties:
-      '#interrupt-cells':
-        const: 1
-
-      compatible:
-        oneOf:
-          - items:
-              - const: andestech,cpu-intc
-              - const: riscv,cpu-intc
-          - const: riscv,cpu-intc
-
-      interrupt-controller: true
-
-    required:
-      - '#interrupt-cells'
-      - compatible
-      - interrupt-controller
+    $ref: /schemas/interrupt-controller/riscv,cpu-intc.yaml#
 
   cpu-idle-states:
     $ref: /schemas/types.yaml#/definitions/phandle-array