vduse: missing error code in vduse_init()

This should return -ENOMEM if alloc_workqueue() fails.  Currently it
returns success.

Fixes: b66219796563 ("vduse: Introduce VDUSE - vDPA Device in Userspace")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/20210907073223.GA18254@kiliSigned-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Xie Yongji <xieyongji@bytedance.com>
Acked-by: Jason Wang <jasowang@redhat.com>

drivers/vdpa/vdpa_user/vduse_dev.c

@@ -1593,8 +1593,10 @@ static int vduse_init(void)
 
 	vduse_irq_wq = alloc_workqueue("vduse-irq",
 				WQ_HIGHPRI | WQ_SYSFS | WQ_UNBOUND, 0);
-	if (!vduse_irq_wq)
+	if (!vduse_irq_wq) {
+		ret = -ENOMEM;
 		goto err_wq;
+	}
 
 	ret = vduse_domain_init();
 	if (ret)