[vlan] Add non-error debug messages

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/net/vlan.c

 	/* Synchronise with trunk device */
 	vlan_sync ( netdev );
 
+	DBGC ( netdev, "VLAN %s created with tag %d and priority %d\n",
+	       netdev->name, vlan->tag, vlan->priority );
+
 	return 0;
 
 	unregister_netdev ( netdev );
 		return -ENOTTY;
 	}
 
+	DBGC ( netdev, "VLAN %s destroyed\n", netdev->name );
+
 	/* Remove VLAN device */
 	unregister_netdev ( netdev );
 	trunk = vlan->trunk;