nvme: fix admin queue depth

BugLink: http://bugs.launchpad.net/bugs/1531539

The number in tag_set->queue depth includes the reserved tags.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
(cherry picked from commit 46800720)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

drivers/nvme/host/pci.c

@@ -1431,7 +1431,7 @@ static int nvme_alloc_admin_tags(struct nvme_dev *dev)
 	if (!dev->ctrl.admin_q) {
 		dev->admin_tagset.ops = &nvme_mq_admin_ops;
 		dev->admin_tagset.nr_hw_queues = 1;
-		dev->admin_tagset.queue_depth = NVME_AQ_DEPTH - 1;
+		dev->admin_tagset.queue_depth = NVME_AQ_DEPTH;
 		dev->admin_tagset.reserved_tags = 1;
 		dev->admin_tagset.timeout = ADMIN_TIMEOUT;
 		dev->admin_tagset.numa_node = dev_to_node(dev->dev);