rcu: Remove obsolete descriptions for rcu_barrier tracepoint

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

include/trace/events/rcu.h

@@ -713,8 +713,6 @@ TRACE_EVENT_RCU(rcu_torture_read,
  *	"Begin": rcu_barrier() started.
  *	"EarlyExit": rcu_barrier() piggybacked, thus early exit.
  *	"Inc1": rcu_barrier() piggyback check counter incremented.
- *	"OfflineNoCB": rcu_barrier() found callback on never-online CPU
- *	"OnlineNoCB": rcu_barrier() found online no-CBs CPU.
  *	"OnlineQ": rcu_barrier() found online CPU with callbacks.
  *	"OnlineNQ": rcu_barrier() found online CPU, no callbacks.
  *	"IRQ": An rcu_barrier_callback() callback posted on remote CPU.