sched/rt: Update comment in pick_next_task_rt()

Commit:

  f4ebcbc ("sched/rt: Substract number of tasks of throttled queues from rq->nr_running")

added a new rt_rq->rt_queued field, which is used to indicate the status of
rq->rt enqueue or dequeue. So, the ->rt_nr_running check was removed and we
now check ->rt_queued instead.

Fix the comment in pick_next_task_rt() as well, which was still referencing
the old logic.

Signed-off-by: Muchun Song <smuchun@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20181027030517.23292-1-smuchun@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/sched/rt.c

@@ -1561,7 +1561,7 @@ pick_next_task_rt(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
 
 	/*
 	 * We may dequeue prev's rt_rq in put_prev_task().
-	 * So, we update time before rt_nr_running check.
+	 * So, we update time before rt_queued check.
 	 */
 	if (prev->sched_class == &rt_sched_class)
 		update_curr_rt(rq);