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-pca953x.c b/drivers/gpio/gpio-pca953x.c
index 1b9dbf6..babb7bd2 100644
--- a/drivers/gpio/gpio-pca953x.c
+++ b/drivers/gpio/gpio-pca953x.c
@@ -608,7 +608,7 @@ static irqreturn_t pca953x_irq_handler(int irq, void *devid)
 	for (i = 0; i < NBANK(chip); i++) {
 		while (pending[i]) {
 			level = __ffs(pending[i]);
-			handle_nested_irq(irq_find_mapping(chip->gpio_chip.irqdomain,
+			handle_nested_irq(irq_find_mapping(chip->gpio_chip.irq.domain,
 							level + (BANK_SZ * i)));
 			pending[i] &= ~(1 << level);
 			nhandled++;