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-dln2.c b/drivers/gpio/gpio-dln2.c
index aecb847..1dada68 100644
--- a/drivers/gpio/gpio-dln2.c
+++ b/drivers/gpio/gpio-dln2.c
@@ -420,7 +420,7 @@
 		return;
 	}
 
-	irq = irq_find_mapping(dln2->gpio.irqdomain, pin);
+	irq = irq_find_mapping(dln2->gpio.irq.domain, pin);
 	if (!irq) {
 		dev_err(dln2->gpio.parent, "pin %d not mapped to IRQ\n", pin);
 		return;