power: ab8500_charger: Remove deprecated create_singlethread_workqueue

power: ab8500_charger: 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 "charger_wq" is used for the IRQs and checking HW state of
the charger. It has been identity converted.

It has multiple work items viz usb_charger_attached_work, kick_wd_work,
check_vbat_work, check_hw_failure_work, usb_charger_attached_work,
ac_work, ac_charger_attached_work, attach_work and check_usbchgnotok_work,
which require execution ordering. Hence, a dedicated ordered workqueue
has been used here.

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

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