workqueue: make init_workqueues() __init

The only caller of init_workqueues() is do_basic_setup().
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/workqueue.c

@@ -823,7 +823,7 @@ static int __devinit workqueue_cpu_callback(struct notifier_block *nfb,
 	return NOTIFY_OK;
 }
 
-void init_workqueues(void)
+void __init init_workqueues(void)
 {
 	cpu_populated_map = cpu_online_map;
 	singlethread_cpu = first_cpu(cpu_possible_map);