gpio: rcar: Use platform_get_irq() to get the interrupt

platform_get_resource(pdev, IORESOURCE_IRQ, ..) relies on static
allocation of IRQ resources in DT core code, this causes an issue
when using hierarchical interrupt domains using "interrupts" property
in the node as this bypassed the hierarchical setup and messed up the
irq chaining.

In preparation for removal of static setup of IRQ resource from DT core
code use platform_get_irq().
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>

drivers/gpio/gpio-rcar.c

@@ -477,7 +477,6 @@ static void gpio_rcar_enable_inputs(struct gpio_rcar_priv *p)
 static int gpio_rcar_probe(struct platform_device *pdev)
 {
 	struct gpio_rcar_priv *p;
-	struct resource *irq;
 	struct gpio_chip *gpio_chip;
 	struct irq_chip *irq_chip;
 	struct gpio_irq_chip *girq;
@@ -502,12 +501,10 @@ static int gpio_rcar_probe(struct platform_device *pdev)
 
 	pm_runtime_enable(dev);
 
-	irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
-	if (!irq) {
-		dev_err(dev, "missing IRQ\n");
-		ret = -EINVAL;
+	ret = platform_get_irq(pdev, 0);
+	if (ret < 0)
 		goto err0;
-	}
+	p->irq_parent = ret;
 
 	p->base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(p->base)) {
@@ -555,8 +552,7 @@ static int gpio_rcar_probe(struct platform_device *pdev)
 		goto err0;
 	}
 
-	p->irq_parent = irq->start;
-	if (devm_request_irq(dev, irq->start, gpio_rcar_irq_handler,
+	if (devm_request_irq(dev, p->irq_parent, gpio_rcar_irq_handler,
 			     IRQF_SHARED, name, p)) {
 		dev_err(dev, "failed to request IRQ\n");
 		ret = -ENOENT;