dt-binding: can: mcp251xfd: include common CAN controller bindings

Since commit

| 1f923440 ("dt-bindings: can: add can-controller.yaml")

there is a common CAN controller binding. Add this to the mcp251xfd
binding.

Link: https://lore.kernel.org/all/20220124220653.3477172-2-mkl@pengutronix.de
Cc: Manivannan Sadhasivam <mani@kernel.org>
Cc: Thomas Kopp <thomas.kopp@microchip.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

Documentation/devicetree/bindings/net/can/microchip,mcp251xfd.yaml

@@ -11,6 +11,9 @@ title:
 maintainers:
   - Marc Kleine-Budde <mkl@pengutronix.de>
 
+allOf:
+  - $ref: can-controller.yaml#
+
 properties:
   compatible:
     oneOf: