workqueue: make deferrable delayed_work initializer names consistent

Initalizers for deferrable delayed_work are confused.

* __DEFERRED_WORK_INITIALIZER()
* DECLARE_DEFERRED_WORK()
* INIT_DELAYED_WORK_DEFERRABLE()

Rename them to

* __DEFERRABLE_WORK_INITIALIZER()
* DECLARE_DEFERRABLE_WORK()
* INIT_DEFERRABLE_WORK()

This patch doesn't cause any functional changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/mm/vmstat.c b/mm/vmstat.c
index df7a674..b3e3b9d 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1157,7 +1157,7 @@
 {
 	struct delayed_work *work = &per_cpu(vmstat_work, cpu);
 
-	INIT_DELAYED_WORK_DEFERRABLE(work, vmstat_update);
+	INIT_DEFERRABLE_WORK(work, vmstat_update);
 	schedule_delayed_work_on(cpu, work, __round_jiffies_relative(HZ, cpu));
 }