atl1: fix resume

adapter->cmb.cmb is initialized when the device is opened and freed when
it's closed. Accessing it unconditionally during resume results either
in a crash (NULL pointer dereference, when the interface has not been
opened yet) or data corruption (when the interface has been used and
brought down adapter->cmb.cmb points to a deallocated memory area).

Cc: stable@kernel.org
Signed-off-by: Luca Tettamanti <kronos.it@gmail.com>
Acked-by: Chris Snook <chris.snook@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/atlx/atl1.c

@@ -2847,10 +2847,11 @@ static int atl1_resume(struct pci_dev *pdev)
 	pci_enable_wake(pdev, PCI_D3cold, 0);
 
 	atl1_reset_hw(&adapter->hw);
-	adapter->cmb.cmb->int_stats = 0;
 
-	if (netif_running(netdev))
+	if (netif_running(netdev)) {
+		adapter->cmb.cmb->int_stats = 0;
 		atl1_up(adapter);
+	}
 	netif_device_attach(netdev);
 
 	return 0;