IB/mlx5: Remove deprecated create_singlethread_workqueue

alloc_ordered_workqueue() with WQ_MEM_RECLAIM set, replaces
deprecated create_singlethread_workqueue(). This is the identity
conversion.

The workqueue "cache->wq" queues work items &ent->work (maps to
cache_work_func) and &ent->dwork(maps to delayed_cache_work_func).
It has been identity converted.

WQ_MEM_RECLAIM has been set to ensure forward progress under
memory pressure.
Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@gmail.com>
Acked-by: Leon Romanovsky <leonro@mellanox.com>
Acked-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/mlx5/mr.c

@@ -611,7 +611,7 @@ int mlx5_mr_cache_init(struct mlx5_ib_dev *dev)
 	int err;
 	int i;
 
-	cache->wq = create_singlethread_workqueue("mkey_cache");
+	cache->wq = alloc_ordered_workqueue("mkey_cache", WQ_MEM_RECLAIM);
 	if (!cache->wq) {
 		mlx5_ib_warn(dev, "failed to create work queue\n");
 		return -ENOMEM;