dt-bindings: net: renesas,ethertsn: Document default for delays

The internal delay properties are not mandatory and should have a
documented default value. The device only supports either no delay or a
fixed delay and the device reset default is no delay, document the
default as no delay.

Signed-off-by: Niklas Söderlund <[e-mail]>
Reviewed-by: Geert Uytterhoeven <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

Documentation/devicetree/bindings/net/renesas,ethertsn.yaml

···
 
   rx-internal-delay-ps:
     enum: [0, 1800]
+    default: 0
 
   tx-internal-delay-ps:
     enum: [0, 2000]
+    default: 0
 
   '#address-cells':
     const: 1