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>

drivers/gpio/gpio-merrifield.c

@@ -357,7 +357,7 @@ static void mrfld_irq_handler(struct irq_desc *desc)
 		for_each_set_bit(gpio, &pending, 32) {
 			unsigned int irq;
 
-			irq = irq_find_mapping(gc->irqdomain, base + gpio);
+			irq = irq_find_mapping(gc->irq.domain, base + gpio);
 			generic_handle_irq(irq);
 		}
 	}