Fix the rcutorturename field so that its size is correctly reported in
the text format embedded in trace.dat files. As it stands, it is
reported as being of size 1:

    field:char rcutorturename[8];   offset:8;       size:1; signed:0;
Signed-off-by: Douglas Raillard <douglas.raillard@arm.com>
Reviewed-by: Mukesh Ojha <quic_mojha@quicinc.com>
Cc: stable@vger.kernel.org
Fixes: 04ae87a5 ("ftrace: Rework event_create_dir()")
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
[ boqun: Add "Cc" and "Fixes" tags per Steven ]
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>