dt-bindings: net: dsa: microchip: add interrupts property for ksz switches

The ksz switch driver allows specifying an interrupt line to prevent
having to periodically poll the switch for link ups/downs and other
asynchronous events.
Signed-off-by: Leonard Göhrs <l.goehrs@pengutronix.de>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>

Documentation/devicetree/bindings/net/dsa/microchip,ksz.yaml

@@ -49,6 +49,9 @@ properties:
       Set if the output SYNCLKO clock should be disabled. Do not mix with
       microchip,synclko-125.
 
+  interrupts:
+    maxItems: 1
+
 required:
   - compatible
   - reg