rcutorture: Create config files for scripted test-the-test testing

This commit adds a pair of files in the configs directory to allow
test-the-test runs of rcutorture via a "--configs BUSTED" argument to
the kvm.sh script.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>

tools/testing/selftests/rcutorture/configs/BUSTED

+CONFIG_RCU_TRACE=n
+CONFIG_SMP=y
+CONFIG_NR_CPUS=4
+CONFIG_HOTPLUG_CPU=y
+CONFIG_PREEMPT_NONE=n
+CONFIG_PREEMPT_VOLUNTARY=n
+CONFIG_PREEMPT=y
+CONFIG_PRINTK_TIME=y

tools/testing/selftests/rcutorture/configs/BUSTED.boot

+rcutorture.torture_type=rcu_busted