scsi: qla2xxx: fix a potential NULL pointer dereference

alloc_workqueue is not checked for errors and as a result a potential
NULL dereference could occur.

Link: https://lore.kernel.org/r/1568824618-4366-1-git-send-email-allen.pais@oracle.comSigned-off-by: Allen Pais <allen.pais@oracle.com>
Reviewed-by: Martin Wilck <mwilck@suse.com>
Acked-by: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/qla2xxx/qla_os.c

@@ -3224,6 +3224,10 @@ qla2x00_probe_one(struct pci_dev *pdev, const struct pci_device_id *id)
 	    req->req_q_in, req->req_q_out, rsp->rsp_q_in, rsp->rsp_q_out);
 
 	ha->wq = alloc_workqueue("qla2xxx_wq", 0, 0);
+	if (unlikely(!ha->wq)) {
+		ret = -ENOMEM;
+		goto probe_failed;
+	}
 
 	if (ha->isp_ops->initialize_adapter(base_vha)) {
 		ql_log(ql_log_fatal, base_vha, 0x00d6,