sched/wake_q: Clarify queue reinit comment

As of:

  bcc9a76d ("locking/rwsem: Reinit wake_q after use")

the comment regarding the list reinitialization no longer applies,
update it with the new wake_q_init() helper.
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Acked-by: Waiman Long <longman@redhat.com>
Cc: peterz@infradead.org
Cc: longman@redhat.com
Cc: akpm@linux-foundation.org
Cc: paulmck@linux.vnet.ibm.com
Cc: torvalds@linux-foundation.org
Link: http://lkml.kernel.org/r/20170129151531.GA2444@linux-80c1.suseSigned-off-by: Ingo Molnar <mingo@kernel.org>

include/linux/sched.h

@@ -1000,8 +1000,8 @@ enum cpu_idle_type {
  *
  * The DEFINE_WAKE_Q macro declares and initializes the list head.
  * wake_up_q() does NOT reinitialize the list; it's expected to be
- * called near the end of a function, where the fact that the queue is
- * not used again will be easy to see by inspection.
+ * called near the end of a function. Otherwise, the list can be
+ * re-initialized for later re-use by wake_q_init().
  *
  * Note that this can cause spurious wakeups. schedule() callers
  * must ensure the call is done inside a loop, confirming that the