rcutorture: Exempt TREE01 from forward-progress testing

Because TREE01 can end up running more vCPUs that physical CPUs,
hammering these shortchanged CPUs with tight loops containing call_rcu()
invocations seems a bit like overkill.  This commit therefore exempts
TREE01 from rcutorture's forward-progress testing.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>

tools/testing/selftests/rcutorture/configs/rcu/TREE01.boot

@@ -3,3 +3,4 @@ rcutree.gp_preinit_delay=3
 rcutree.gp_init_delay=3
 rcutree.gp_cleanup_delay=3
 rcu_nocbs=0
+rcutorture.fwd_progress=0