workqueue: Remove deprecated __cancel_delayed_work()

__cancel_delayed_work() was deprecated by 136b5721d75a ("workqueue:
deprecate __cancel_delayed_work()") as cancel_delayed_work() was
updated so that it could be used from all contexts.  Enough time has
passed since the deprecation.  Let's remove it.

tj: description update

Signed-off-by: Tan Xiaojun <tanxiaojun@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

include/linux/workqueue.h

@@ -605,21 +605,6 @@ static inline bool keventd_up(void)
 	return system_wq != NULL;
 }
 
-/*
- * Like above, but uses del_timer() instead of del_timer_sync(). This means,
- * if it returns 0 the timer function may be running and the queueing is in
- * progress.
- */
-static inline bool __deprecated __cancel_delayed_work(struct delayed_work *work)
-{
-	bool ret;
-
-	ret = del_timer(&work->timer);
-	if (ret)
-		work_clear_pending(&work->work);
-	return ret;
-}
-
 /* used to be different but now identical to flush_work(), deprecated */
 static inline bool __deprecated flush_work_sync(struct work_struct *work)
 {