rcu: Update descriptions for rcu_future_grace_period tracepoint

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

include/trace/events/rcu.h

@@ -93,16 +93,16 @@ TRACE_EVENT_RCU(rcu_grace_period,
  * the data from the rcu_node structure, other than rcuname, which comes
  * from the rcu_state structure, and event, which is one of the following:
  *
- * "Startleaf": Request a grace period based on leaf-node data.
+ * "Cleanup": Clean up rcu_node structure after previous GP.
+ * "CleanupMore": Clean up, and another GP is needed.
+ * "EndWait": Complete wait.
+ * "NoGPkthread": The RCU grace-period kthread has not yet started.
  * "Prestarted": Someone beat us to the request
  * "Startedleaf": Leaf node marked for future GP.
  * "Startedleafroot": All nodes from leaf to root marked for future GP.
  * "Startedroot": Requested a nocb grace period based on root-node data.
- * "NoGPkthread": The RCU grace-period kthread has not yet started.
+ * "Startleaf": Request a grace period based on leaf-node data.
  * "StartWait": Start waiting for the requested grace period.
- * "EndWait": Complete wait.
- * "Cleanup": Clean up rcu_node structure after previous GP.
- * "CleanupMore": Clean up, and another GP is needed.
  */
 TRACE_EVENT_RCU(rcu_future_grace_period,