i40iw_cm: 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 "event_wq" is involved in event handling and queues
i40iw_cm_event_handler.

The workqueue "disconn_wq" is involved in closing connection and queues
i40iw_disconnect_worker.

Both workqueues have been identity converted.

WQ_MEM_RECLAIM has been set to ensure forward progress under memory
pressure.

Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@gmail.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>