power: intel_mid_battery: Remove deprecated create_singlethread_workqueue

The workqueue "monitor_wqueue" is used to monitor the PMIC battery status.
It queues a single work item (pbi->monitor_battery) and hence doesn't
require ordering. Hence, alloc_workqueue has been used to replace the
deprecated create_singlethread_workqueue instance.

Since PMIC battery status needs to be monitored for any change, the
WQ_MEM_RECLAIM flag has been set to ensure forward progress under memory
pressure.

Since there is a single work item, explicit concurrency
limit is unnecessary here.

Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@gmail.com>
Signed-off-by: Sebastian Reichel <sre@kernel.org>