nvme: fix an error code in nvme_init_subsystem()

"ret" should be a negative error code here, but it's either success or
possibly uninitialized.

Fixes: 32fd90c ("nvme: change locking for the per-subsystem controller list")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>

drivers/nvme/host/core.c

@@ -2543,8 +2543,9 @@ static int nvme_init_subsystem(struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id)
 		list_add_tail(&subsys->entry, &nvme_subsystems);
 	}
 
-	if (sysfs_create_link(&subsys->dev.kobj, &ctrl->device->kobj,
-			dev_name(ctrl->device))) {
+	ret = sysfs_create_link(&subsys->dev.kobj, &ctrl->device->kobj,
+				dev_name(ctrl->device));
+	if (ret) {
 		dev_err(ctrl->device,
 			"failed to create sysfs link from subsystem.\n");
 		goto out_put_subsystem;