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

commit 128ea9f6cc ("workqueue: Add system_percpu_wq and system_dfl_wq")
commit 930c2ea566 ("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/20251106141955.218911-2-marco.crivellari@suse.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/keyboard/gpio_keys.c

@@ -434,7 +434,7 @@ static irqreturn_t gpio_keys_gpio_isr(int irq, void *dev_id)
 			      ms_to_ktime(bdata->software_debounce),
 			      HRTIMER_MODE_REL);
 	} else {
-		mod_delayed_work(system_wq,
+		mod_delayed_work(system_dfl_wq,
 				 &bdata->work,
 				 msecs_to_jiffies(bdata->software_debounce));
 	}