Remove redundant up() in stop_machine()

An up() is called in kernel/stop_machine.c on failure, and also in the
caller (unconditionally).
Signed-off-by: Zhou Yingchao <yingchao.zhou@gmail.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>

kernel/stop_machine.c

@@ -111,7 +111,6 @@ static int stop_machine(void)
 	/* If some failed, kill them all. */
 	if (ret < 0) {
 		stopmachine_set_state(STOPMACHINE_EXIT);
-		up(&stopmachine_mutex);
 		return ret;
 	}