regulator: irq_helper: replace use of system_wq with system_dfl_wq

Currently if a user enqueues a work item using schedule_delayed_work() the
used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
schedule_work() that is using system_wq and queue_work(), that makes use
again of WORK_CPU_UNBOUND.

This lack of consistency cannot be addressed without refactoring the API.

This continues the effort to refactor worqueue APIs, which has begun
with the change introducing new workqueues and a new alloc_workqueue flag:

commit 128ea9f ("workqueue: Add system_percpu_wq and system_dfl_wq")
commit 930c2ea ("workqueue: Add new WQ_PERCPU flag")

This specific workload do not benefit from a per-cpu workqueue, so use
the default unbound workqueue (system_dfl_wq) instead.

Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Marco Crivellari <marco.crivellari@suse.com>
Link: https://patch.msgid.link/20251106142914.227875-1-marco.crivellari@suse.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: DispatchCode

drivers/regulator/irq_helpers.c

@@ -146,7 +146,7 @@ static void regulator_notifier_isr_work(struct work_struct *work)
 
 reschedule:
 	if (!d->high_prio)
-		mod_delayed_work(system_wq, &h->isr_work,
+		mod_delayed_work(system_dfl_wq, &h->isr_work,
 				 msecs_to_jiffies(tmo));
 	else
 		mod_delayed_work(system_highpri_wq, &h->isr_work,