rcu: Have rcutiny tracepoints use tracepoint_string()

This commit extends the work done in f7f7bac9 (rcu: Have the RCU
tracepoints use the tracepoint_string infrastructure) to cover rcutiny.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>

diff --cc kernel/rcu.h
Simple merge

diff --cc kernel/rcutiny.c
Simple merge

diff --cc kernel/rcutree.c
Simple merge