rcu: Remove event tracing from rcu_cpu_notify(), used by offline CPUs

Offline CPUs cannot safely invoke trace events, but such CPUs do execute
within rcu_cpu_notify().  Therefore, this commit removes the trace events
from rcu_cpu_notify().  These trace events are for utilization, against
which rcu_cpu_notify() execution time should be negligible.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>