sky2: fix oops on shutdown

If the device is fails during module startup for some reason like
unsupported chip version then the driver would crash dereferencing a
null pointer, on shutdown or suspend/resume.
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/net/sky2.c

@@ -3732,6 +3732,7 @@ static int __devinit sky2_probe(struct pci_dev *pdev,
 err_out_disable:
 	pci_disable_device(pdev);
 err_out:
+	pci_set_drvdata(pdev, NULL);
 	return err;
 }
 
@@ -3784,6 +3785,9 @@ static int sky2_suspend(struct pci_dev *pdev, pm_message_t state)
 	struct sky2_hw *hw = pci_get_drvdata(pdev);
 	int i, wol = 0;
 
+	if (!hw)
+		return 0;
+
 	del_timer_sync(&hw->idle_timer);
 	netif_poll_disable(hw->dev[0]);
 
@@ -3815,6 +3819,9 @@ static int sky2_resume(struct pci_dev *pdev)
 	struct sky2_hw *hw = pci_get_drvdata(pdev);
 	int i, err;
 
+	if (!hw)
+		return 0;
+
 	err = pci_set_power_state(pdev, PCI_D0);
 	if (err)
 		goto out;
@@ -3861,6 +3868,9 @@ static void sky2_shutdown(struct pci_dev *pdev)
 	struct sky2_hw *hw = pci_get_drvdata(pdev);
 	int i, wol = 0;
 
+	if (!hw)
+		return;
+
 	del_timer_sync(&hw->idle_timer);
 	netif_poll_disable(hw->dev[0]);