rcutorture: Adjust rcu_poll_need_2gp() for rcu_gp_oldstate field removal

Now that rcu_gp_oldstate can accurately track both normal and
expedited grace periods regardless of system state, rcutorture's
rcu_poll_need_2gp() function need only call for a second grace period
for the old single-unsigned-long grace-period polling APIs
This commit therefore adjusts rcu_poll_need_2gp() accordingly.
Signed-off-by: NPaul E. McKenney <paulmck@kernel.org>

kernel/rcu/rcutorture.c

@@ -520,7 +520,7 @@ static void rcu_sync_torture_init(void)
 
 static bool rcu_poll_need_2gp(bool poll, bool poll_full)
 {
-	return poll || (!IS_ENABLED(CONFIG_TINY_RCU) && poll_full && num_online_cpus() <= 1);
+	return poll;
 }
 
 static struct rcu_torture_ops rcu_ops = {