gpio: Move irqdomain into struct gpio_irq_chip

In order to consolidate the multiple ways to associate an IRQ chip with
a GPIO chip, move more fields into the new struct gpio_irq_chip.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Acked-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/gpio/gpio-pcf857x.c b/drivers/gpio/gpio-pcf857x.c
index a4fd78b..38fbb42 100644
--- a/drivers/gpio/gpio-pcf857x.c
+++ b/drivers/gpio/gpio-pcf857x.c
@@ -196,7 +196,7 @@
 	mutex_unlock(&gpio->lock);
 
 	for_each_set_bit(i, &change, gpio->chip.ngpio)
-		handle_nested_irq(irq_find_mapping(gpio->chip.irqdomain, i));
+		handle_nested_irq(irq_find_mapping(gpio->chip.irq.domain, i));
 
 	return IRQ_HANDLED;
 }