cpuset: remove unused cpuset_unlock()

Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NLi Zefan <lizefan@huawei.com>

kernel/cpuset.c

@@ -2411,17 +2411,6 @@ int __cpuset_node_allowed_hardwall(int node, gfp_t gfp_mask)
 	return 0;
 }
 
-/**
- * cpuset_unlock - release lock on cpuset changes
- *
- * Undo the lock taken in a previous cpuset_lock() call.
- */
-
-void cpuset_unlock(void)
-{
-	mutex_unlock(&callback_mutex);
-}
-
 /**
  * cpuset_mem_spread_node() - On which node to begin search for a file page
  * cpuset_slab_spread_node() - On which node to begin search for a slab page