cgroup/cpuset: simplify the percpu kthreads check in update_tasks_cpumask()

kthread_is_per_cpu() can be called directly without checking whether
PF_KTHREAD is set in task->flags. So remove PF_KTHREAD check to make
code more concise.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

kernel/cgroup/cpuset.c

@@ -1230,7 +1230,7 @@ static void update_tasks_cpumask(struct cpuset *cs, struct cpumask *new_cpus)
 			/*
 			 * Percpu kthreads in top_cpuset are ignored
 			 */
-			if ((task->flags & PF_KTHREAD) && kthread_is_per_cpu(task))
+			if (kthread_is_per_cpu(task))
 				continue;
 			cpumask_andnot(new_cpus, possible_mask, cs->subparts_cpus);
 		} else {