igb: do a reset on SR-IOV re-init if device is down

To properly re-initialize SR-IOV it is necessary to reset the device
even if it is already down. Not doing this may result in Tx unit hangs.

Cc: stable <stable@vger.kernel.org>
Signed-off-by: NStefan Assmann <sassmann@kpanic.de>
Tested-by: NAaron Brown <aaron.f.brown@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/intel/igb/igb_main.c

@@ -7592,6 +7592,8 @@ static int igb_sriov_reinit(struct pci_dev *dev)
 
 	if (netif_running(netdev))
 		igb_close(netdev);
+	else
+		igb_reset(adapter);
 
 	igb_clear_interrupt_scheme(adapter);