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-stmpe.c b/drivers/gpio/gpio-stmpe.c
index 001a89d..18d8bef 100644
--- a/drivers/gpio/gpio-stmpe.c
+++ b/drivers/gpio/gpio-stmpe.c
@@ -397,7 +397,7 @@ static irqreturn_t stmpe_gpio_irq(int irq, void *dev)
 		while (stat) {
 			int bit = __ffs(stat);
 			int line = bank * 8 + bit;
-			int child_irq = irq_find_mapping(stmpe_gpio->chip.irqdomain,
+			int child_irq = irq_find_mapping(stmpe_gpio->chip.irq.domain,
 							 line);
 
 			handle_nested_irq(child_irq);