TREE03 has been especially effective at finding bugs lately.  This commit
makes it even more effective by speeding up its CPU hotplug testing and
increasing its NR_CPUs from 8 to 16.  TREE08's NR_CPUS is decreased from
16 to 8 in order to maintain the same test duration.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>