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>

drivers/gpio/gpio-zx.c

@@ -170,7 +170,7 @@ static void zx_irq_handler(struct irq_desc *desc)
 	writew_relaxed(pending, chip->base + ZX_GPIO_IC);
 	if (pending) {
 		for_each_set_bit(offset, &pending, ZX_GPIO_NR)
-			generic_handle_irq(irq_find_mapping(gc->irqdomain,
+			generic_handle_irq(irq_find_mapping(gc->irq.domain,
 							    offset));
 	}