workqueue: mark init_workqueues() as early_initcall()

Mark init_workqueues() as early_initcall() and thus it will be initialized
before smp bringup. init_workqueues() registers for the hotcpu notifier
and thus it should cope with the processors that are brought online after
the workqueues are initialized.

x86 smp bringup code uses workqueues and uses a workaround for the
cold boot process (as the workqueues are initialized post smp_init()).
Marking init_workqueues() as early_initcall() will pave the way for
cleaning up this code.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 1105c47..e2eb351 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -3507,7 +3507,7 @@
 }
 #endif /* CONFIG_FREEZER */
 
-void __init init_workqueues(void)
+static int __init init_workqueues(void)
 {
 	unsigned int cpu;
 	int i;
@@ -3559,4 +3559,6 @@
 	system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND,
 					    WQ_UNBOUND_MAX_ACTIVE);
 	BUG_ON(!system_wq || !system_long_wq || !system_nrt_wq);
+	return 0;
 }
+early_initcall(init_workqueues);