srcu: Make rcutorture dump the SRCU size state

This commit adds the numeric and string version of ->srcu_size_state to
the Tree-SRCU-specific portion of the rcutorture output.

[ paulmck: Apply feedback from kernel test robot and Dan Carpenter. ]
[ quic_neeraju: Apply feedback from Jiapeng Chong. ]

Co-developed-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>