rcu-tasks: Correct firstreport usage in check_all_holdout_tasks_trace

In check_all_holdout_tasks_trace(), firstreport is a pointer argument;
so, check the dereferenced value, instead of checking the pointer.
Signed-off-by: Neeraj Upadhyay <neeraju@codeaurora.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

kernel/rcu/tasks.h

@@ -1129,7 +1129,7 @@ static void check_all_holdout_tasks_trace(struct list_head *hop,
 	cpus_read_unlock();
 
 	if (needreport) {
-		if (firstreport)
+		if (*firstreport)
 			pr_err("INFO: rcu_tasks_trace detected stalls? (Late IPI?)\n");
 		show_stalled_ipi_trace();
 	}