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-lynxpoint.c b/drivers/gpio/gpio-lynxpoint.c
index fbd393b..1e557b1 100644
--- a/drivers/gpio/gpio-lynxpoint.c
+++ b/drivers/gpio/gpio-lynxpoint.c
@@ -255,7 +255,7 @@ static void lp_gpio_irq_handler(struct irq_desc *desc)
 			mask = BIT(pin);
 			/* Clear before handling so we don't lose an edge */
 			outl(mask, reg);
-			irq = irq_find_mapping(lg->chip.irqdomain, base + pin);
+			irq = irq_find_mapping(lg->chip.irq.domain, base + pin);
 			generic_handle_irq(irq);
 		}
 	}