igb: fix null pointer dereference seen with fiber NICs

With a fiber or serdes NIC installed the driver was causing a null pointer
dereference on driver unload.
Signed-off-by: NAlexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

drivers/net/igb/igb_main.c

@@ -1372,7 +1372,8 @@ static void __devexit igb_remove(struct pci_dev *pdev)
 
 	unregister_netdev(netdev);
 
-	if (!igb_check_reset_block(&adapter->hw))
+	if (adapter->hw.phy.ops.reset_phy &&
+	    !igb_check_reset_block(&adapter->hw))
 		adapter->hw.phy.ops.reset_phy(&adapter->hw);
 
 	igb_remove_device(&adapter->hw);