net: thunder: Fix crash upon shutdown after failed probe

If device probe fails, driver remains bound to the PCI device. However,
driver data has been reset to NULL. This causes crash upon dereferencing
it in nicvf_remove()
Signed-off-by: NPavel Fedin <p.fedin@samsung.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/cavium/thunder/nicvf_main.c

@@ -1600,6 +1600,9 @@ static void nicvf_remove(struct pci_dev *pdev)
 
 static void nicvf_shutdown(struct pci_dev *pdev)
 {
+	if (!pci_get_drvdata(pdev))
+		return;
+
 	nicvf_remove(pdev);
 }