block: Fix two comments that refer to .queue_rq() return values

Since patch "blk-mq: switch .queue_rq return value to blk_status_t"
.queue_rq() returns a BLK_STS_* value instead of a BLK_MQ_RQ_*
value. Hence refer to the former in comments about .queue_rq()
return values.

Fixes: commit 39a70c76 ("blk-mq: clarify dispatch may not be drained/blocked by stopping queue")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-mq.c

@@ -1258,7 +1258,7 @@ EXPORT_SYMBOL(blk_mq_queue_stopped);
 /*
  * This function is often used for pausing .queue_rq() by driver when
  * there isn't enough resource or some conditions aren't satisfied, and
- * BLK_MQ_RQ_QUEUE_BUSY is usually returned.
+ * BLK_STS_RESOURCE is usually returned.
  *
  * We do not guarantee that dispatch can be drained or blocked
  * after blk_mq_stop_hw_queue() returns. Please use
@@ -1275,7 +1275,7 @@ EXPORT_SYMBOL(blk_mq_stop_hw_queue);
 /*
  * This function is often used for pausing .queue_rq() by driver when
  * there isn't enough resource or some conditions aren't satisfied, and
- * BLK_MQ_RQ_QUEUE_BUSY is usually returned.
+ * BLK_STS_RESOURCE is usually returned.
  *
  * We do not guarantee that dispatch can be drained or blocked
  * after blk_mq_stop_hw_queues() returns. Please use