workqueue: Fix workqueue_execute_end() comment

workqueue_execute_end() is called after the callback function,
not before.
Signed-off-by: NStephen Boyd <sboyd@codeaurora.org>
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

include/trace/events/workqueue.h

@@ -103,7 +103,7 @@ TRACE_EVENT(workqueue_execute_start,
 );
 
 /**
- * workqueue_execute_end - called immediately before the workqueue callback
+ * workqueue_execute_end - called immediately after the workqueue callback
  * @work:	pointer to struct work_struct
  *
  * Allows to track workqueue execution.