fm10k: Remove create_workqueue

alloc_workqueue replaces deprecated create_workqueue().

A dedicated workqueue has been used since the workitem (viz
fm10k_service_task, which manages and runs other subtasks) is involved in
normal device operation and requires forward progress under memory
pressure.

create_workqueue has been replaced with alloc_workqueue with max_active
as 0 since there is no need for throttling the number of active work
items.

Since network devices may be used in memory reclaim path,
WQ_MEM_RECLAIM has been set to guarantee forward progress.

flush_workqueue is unnecessary since destroy_workqueue() itself calls
drain_workqueue() which flushes repeatedly till the workqueue
becomes empty. Hence the call to flush_workqueue() has been dropped.

Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>