gpio: siox: explicitly support only threaded irqs

The gpio-siox driver uses handle_nested_irq() to implement its
interrupt support. This is only capable of handling threaded irq
actions. For a hardirq action it triggers a NULL pointer oops.
(It calls action->thread_fn which is NULL then.)

Prevent registration of a hardirq action by setting
gpio_irq_chip::threaded to true.

Cc: u.kleine-koenig@pengutronix.de
Fixes: be8c8fac ("gpio: new driver to work with a 8x12 siox")
Cc: stable@vger.kernel.org
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>

drivers/gpio/gpio-siox.c

@@ -245,6 +245,7 @@ static int gpio_siox_probe(struct siox_device *sdevice)
 	girq->chip = &ddata->ichip;
 	girq->default_type = IRQ_TYPE_NONE;
 	girq->handler = handle_level_irq;
+	girq->threaded = true;
 
 	ret = devm_gpiochip_add_data(dev, &ddata->gchip, NULL);
 	if (ret)