nvme-loop: get rid of unused controller lock

Signed-off-by: NSagi Grimberg <sagi@grimberg.me>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

drivers/nvme/target/loop.c

@@ -45,7 +45,6 @@ struct nvme_loop_iod {
 };
 
 struct nvme_loop_ctrl {
-	spinlock_t		lock;
 	struct nvme_loop_queue	*queues;
 	u32			queue_count;
 
@@ -635,8 +634,6 @@ static struct nvme_ctrl *nvme_loop_create_ctrl(struct device *dev,
 	if (ret)
 		goto out_put_ctrl;
 
-	spin_lock_init(&ctrl->lock);
-
 	ret = -ENOMEM;
 
 	ctrl->ctrl.sqsize = opts->queue_size - 1;