rcutorture: Test RCU-sched primitives in TREE_PREEMPT_RCU kernels

This commit ensures that RCU-sched primitives are tested in
TREE_PREEMPT_RCU kernels, a combination that was previously omitted.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>