net: clean leftover of COMPAT_NET_DEV_OPS removal

COMPAT_NET_DEV_OPS was removed a while back and with it the definition of
netdev_resync_ops() went away. Let's finish the clean-up.
Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -1692,7 +1692,6 @@ extern int 		netdev_refcnt_read(const struct net_device *dev);
 extern void		free_netdev(struct net_device *dev);
 extern void		synchronize_net(void);
 extern int		init_dummy_netdev(struct net_device *dev);
-extern void		netdev_resync_ops(struct net_device *dev);
 
 extern struct net_device	*dev_get_by_index(struct net *net, int ifindex);
 extern struct net_device	*__dev_get_by_index(struct net *net, int ifindex);