blk-wbt: remove outdated comment

Now wbt_wait() returns void, so remove now outdated comment.

Signed-off-by: lijiazi <lijiazi@xiaomi.com>
Link: https://lore.kernel.org/r/1623986240-13878-1-git-send-email-lijiazi@xiaomi.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-wbt.c

@@ -563,7 +563,6 @@ static void wbt_cleanup(struct rq_qos *rqos, struct bio *bio)
 }
 
 /*
- * Returns true if the IO request should be accounted, false if not.
  * May sleep, if we have exceeded the writeback limits. Caller can pass
  * in an irq held spinlock, if it holds one when calling this function.
  * If we do sleep, we'll release and re-grab it.