rcutorture: Remove SRCU-lite scenarios

This commit prepares for the removal of SRCU-Lite by removing the SRCU-L
rcutorture scenario that tests it.

Both SRCU-lite and SRCU-fast provide faster readers by dropping the
smp_mb() call from their lock and unlock primitives, but incur a pair
of added RCU grace periods during the SRCU grace period.  There is a
trivial mapping from the SRCU-lite API to that of SRCU-fast, so there
should be no transition issues.

[ paulmck: Apply Christoph Hellwig feedback. ]

Signed-off-by: "Paul E. McKenney" <paulmck@kernel.org>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>

Author: paulmckrcu

tools/testing/selftests/rcutorture/configs/rcu/CFLIST

@@ -5,7 +5,6 @@ TREE04
 TREE05
 TREE07
 TREE09
-SRCU-L
 SRCU-N
 SRCU-P
 SRCU-T