dt-bindings: can: fsl,flexcan: add transceiver capabilities

Currently the flexcan driver does only support adding PHYs by using the
"old" regulator bindings. Add support for CAN transceivers as a PHY.

Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Dimitri Fedrau <dimitri.fedrau@liebherr.com>
Link: https://patch.msgid.link/20250312-flexcan-add-transceiver-caps-v4-1-29e89ae0225a@liebherr.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

Documentation/devicetree/bindings/net/can/fsl,flexcan.yaml

@@ -77,6 +77,9 @@ properties:
   xceiver-supply:
     description: Regulator that powers the CAN transceiver.
 
+  phys:
+    maxItems: 1
+
   big-endian:
     $ref: /schemas/types.yaml#/definitions/flag
     description: |
@@ -171,6 +174,12 @@ allOf:
         interrupts:
           maxItems: 1
         interrupt-names: false
+  - if:
+      required:
+        - xceiver-supply
+    then:
+      properties:
+        phys: false
 
 additionalProperties: false