libceph: create_singlethread_workqueue() doesn't return ERR_PTRs

create_singlethread_workqueue() returns NULL on error, and it doesn't
return ERR_PTRs.

I tweaked the error handling a little to be consistent with earlier in
the function.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: NSage Weil <sage@inktank.com>

net/ceph/osd_client.c

@@ -2264,12 +2264,10 @@ int ceph_osdc_init(struct ceph_osd_client *osdc, struct ceph_client *client)
 	if (err < 0)
 		goto out_msgpool;
 
+	err = -ENOMEM;
 	osdc->notify_wq = create_singlethread_workqueue("ceph-watch-notify");
-	if (IS_ERR(osdc->notify_wq)) {
-		err = PTR_ERR(osdc->notify_wq);
-		osdc->notify_wq = NULL;
+	if (!osdc->notify_wq)
 		goto out_msgpool;
-	}
 	return 0;
 
 out_msgpool: