sysfs: file.c: use create_singlethread_workqueue()

We don't need a kernel thread per CPU for this application.
Acked-by: NAlex Chiang <achiang@hp.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

fs/sysfs/file.c

@@ -723,7 +723,7 @@ int sysfs_schedule_callback(struct kobject *kobj, void (*func)(void *),
 	mutex_unlock(&sysfs_workq_mutex);
 
 	if (sysfs_workqueue == NULL) {
-		sysfs_workqueue = create_workqueue("sysfsd");
+		sysfs_workqueue = create_singlethread_workqueue("sysfsd");
 		if (sysfs_workqueue == NULL) {
 			module_put(owner);
 			return -ENOMEM;