genirq: Reuse irq_thread_fn() for forced thread case

rq_forced_thread_fn() uses the same action callback as the non-forced
variant but with different locking decorations. Reuse irq_thread_fn() here
to make that clear.

Signed-off-by: Andy Shevchenko <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>
Link: https://lore.kernel.org/all/[e-mail]

kernel/irq/manage.c

···
 	local_bh_disable();
 	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
 		local_irq_disable();
-	ret = action->thread_fn(action->irq, action->dev_id);
-	if (ret == IRQ_HANDLED)
-		atomic_inc(&desc->threads_handled);
-
-	irq_finalize_oneshot(desc, action);
+	ret = irq_thread_fn(desc, action);
 	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
 		local_irq_enable();
 	local_bh_enable();