net: kill netif_copy_real_num_queues()

vlan was the only user of netif_copy_real_num_queues(),
but it no longer calls it after
commit 4af429d2 ("vlan: lockless transmit path").
So we can just remove it.

Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -2762,23 +2762,6 @@ static inline int netif_set_real_num_rx_queues(struct net_device *dev,
 }
 #endif
 
-static inline int netif_copy_real_num_queues(struct net_device *to_dev,
-					     const struct net_device *from_dev)
-{
-	int err;
-
-	err = netif_set_real_num_tx_queues(to_dev,
-					   from_dev->real_num_tx_queues);
-	if (err)
-		return err;
-#ifdef CONFIG_SYSFS
-	return netif_set_real_num_rx_queues(to_dev,
-					    from_dev->real_num_rx_queues);
-#else
-	return 0;
-#endif
-}
-
 #ifdef CONFIG_SYSFS
 static inline unsigned int get_netdev_rx_queue_index(
 		struct netdev_rx_queue *queue)