net: Detect and ignore netif_stop_queue() calls before register_netdev()

After e648493: net: allocate tx queues in register_netdevice
These calls make net drivers oops at load time, so let's avoid people
git-bisect'ing known problems.

Signed-off-by: Guillaume Chazarain <guichaz@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -1554,6 +1554,11 @@ static inline void netif_tx_wake_all_queues(struct net_device *dev)
 
 static inline void netif_tx_stop_queue(struct netdev_queue *dev_queue)
 {
+	if (WARN_ON(!dev_queue)) {
+		printk(KERN_INFO "netif_stop_queue() cannot be called before "
+		       "register_netdev()");
+		return;
+	}
 	set_bit(__QUEUE_STATE_XOFF, &dev_queue->state);
 }