erofs: fix an error code in z_erofs_init_zip_subsystem()

Return -ENOMEM if alloc_workqueue() fails.  Don't return success.

Fixes: d8a650adf429 ("erofs: add per-cpu threads for decompression as an option")
Signed-off-by: Dan Carpenter <error27@gmail.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/Y+4d0FRsUq8jPoOu@kiliSigned-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

fs/erofs/zdata.c

@@ -475,8 +475,10 @@ int __init z_erofs_init_zip_subsystem(void)
 
 	z_erofs_workqueue = alloc_workqueue("erofs_worker",
 			WQ_UNBOUND | WQ_HIGHPRI, num_possible_cpus());
-	if (!z_erofs_workqueue)
+	if (!z_erofs_workqueue) {
+		err = -ENOMEM;
 		goto out_error_workqueue_init;
+	}
 
 	err = erofs_init_percpu_workers();
 	if (err)