workqueue: Remove deprecated flush[_delayed]_work_sync()

flush[_delayed]_work_sync() were deprecated by 43829731 ("workqueue:
deprecate flush[_delayed]_work_sync()") and have been deprecated
for a long time. In addition, these are not used anymore. So,
let's remove these functions.
Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

include/linux/workqueue.h

@@ -587,18 +587,6 @@ static inline bool keventd_up(void)
 	return system_wq != NULL;
 }
 
-/* used to be different but now identical to flush_work(), deprecated */
-static inline bool __deprecated flush_work_sync(struct work_struct *work)
-{
-	return flush_work(work);
-}
-
-/* used to be different but now identical to flush_delayed_work(), deprecated */
-static inline bool __deprecated flush_delayed_work_sync(struct delayed_work *dwork)
-{
-	return flush_delayed_work(dwork);
-}
-
 #ifndef CONFIG_SMP
 static inline long work_on_cpu(int cpu, long (*fn)(void *), void *arg)
 {