usbnet: support net_device_ops

Use net_device_ops for usbnet device, and export for use
by other derived drivers.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/usb/usbnet.h b/include/linux/usb/usbnet.h
index 7d38222..36fabb9 100644
--- a/include/linux/usb/usbnet.h
+++ b/include/linux/usb/usbnet.h
@@ -176,6 +176,11 @@
 	size_t			length;
 };
 
+extern int usbnet_open (struct net_device *net);
+extern int usbnet_stop (struct net_device *net);
+extern int usbnet_start_xmit (struct sk_buff *skb, struct net_device *net);
+extern void usbnet_tx_timeout (struct net_device *net);
+extern int usbnet_change_mtu (struct net_device *net, int new_mtu);
 
 extern int usbnet_get_endpoints(struct usbnet *, struct usb_interface *);
 extern void usbnet_defer_kevent (struct usbnet *, int);