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-ws16c48.c b/drivers/gpio/gpio-ws16c48.c
index 5037974..7466482 100644
--- a/drivers/gpio/gpio-ws16c48.c
+++ b/drivers/gpio/gpio-ws16c48.c
@@ -332,7 +332,7 @@ static irqreturn_t ws16c48_irq_handler(int irq, void *dev_id)
 			int_id = inb(ws16c48gpio->base + 8 + port);
 			for_each_set_bit(gpio, &int_id, 8)
 				generic_handle_irq(irq_find_mapping(
-					chip->irqdomain, gpio + 8*port));
+					chip->irq.domain, gpio + 8*port));
 		}
 
 		int_pending = inb(ws16c48gpio->base + 6) & 0x7;