nvme-fc: avoid workqueue flush stalls

There's no need to wait for the full nvme_wq, which is now shared,
to flush. flush only the delete_work item.
Signed-off-by: James Smart <james.smart@broadcom.com>
Reviewed-by: Sagi Grimberg <sgi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/host/fc.c

@@ -2693,7 +2693,7 @@ nvme_fc_del_nvme_ctrl(struct nvme_ctrl *nctrl)
 	nvme_get_ctrl(&ctrl->ctrl);
 	ret = __nvme_fc_del_ctrl(ctrl);
 	if (!ret)
-		flush_workqueue(nvme_wq);
+		flush_work(&ctrl->delete_work);
 	nvme_put_ctrl(&ctrl->ctrl);
 
 	return ret;