ixgbevf: Set the netdev number of Tx queues

The driver was not setting the number of real Tx queues in the net_device
structure.  This caused some serious issues such as Tx hangs and extremely
poor performance with some usages of the driver.

The issue is best observed by running:

iperf -c <host> -P <n>

Where n is greater than one.  The greater the value of n the more likely
the problem is to show up.
Signed-off-by: Greg Rose <gregory.v.rose@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c

@@ -1747,6 +1747,7 @@ static int ixgbevf_alloc_queues(struct ixgbevf_adapter *adapter)
  **/
 static int ixgbevf_set_interrupt_capability(struct ixgbevf_adapter *adapter)
 {
+	struct net_device *netdev = adapter->netdev;
 	int err = 0;
 	int vector, v_budget;
 
@@ -1775,6 +1776,12 @@ static int ixgbevf_set_interrupt_capability(struct ixgbevf_adapter *adapter)
 
 	ixgbevf_acquire_msix_vectors(adapter, v_budget);
 
+	err = netif_set_real_num_tx_queues(netdev, adapter->num_tx_queues);
+	if (err)
+		goto out;
+
+	err = netif_set_real_num_rx_queues(netdev, adapter->num_rx_queues);
+
 out:
 	return err;
 }