dt-bindings: net: lan966x: Extend with the ptp interrupt

Extend dt-bindings for lan966x with ptp interrupt. This is generated
when doing 2-step timestamping and the timestamp can be read from the
FIFO.

Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/microchip,lan966x-switch.yaml

@@ -38,13 +38,15 @@ properties:
       - description: register based extraction
       - description: frame dma based extraction
       - description: analyzer interrupt
+      - description: ptp interrupt
 
   interrupt-names:
     minItems: 1
     items:
       - const: xtr
       - const: fdma
       - const: ana
+      - const: ptp
 
   resets:
     items: