[SCSI] qla2xxx: Avoid null pointer dereference in shutdown routine.

Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Signed-off-by: Saurav Kashyap <saurav.kashyap@qlogic.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

drivers/scsi/qla2xxx/qla_os.c

@@ -2808,6 +2808,9 @@ qla2x00_shutdown(struct pci_dev *pdev)
 	scsi_qla_host_t *vha;
 	struct qla_hw_data  *ha;
 
+	if (!atomic_read(&pdev->enable_cnt))
+		return;
+
 	vha = pci_get_drvdata(pdev);
 	ha = vha->hw;