thermal/drivers/rcar_thermal: Use platform_get_irq_optional() 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 bypasses the hierarchical setup and messes up the
irq chaining.

In preparation for removal of static setup of IRQ resource from DT core
code use platform_get_irq_optional().
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20220110144039.5810-1-prabhakar.mahadev-lad.rj@bp.renesas.comSigned-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

drivers/thermal/rcar_thermal.c

@@ -445,7 +445,7 @@ static int rcar_thermal_probe(struct platform_device *pdev)
 	struct rcar_thermal_common *common;
 	struct rcar_thermal_priv *priv;
 	struct device *dev = &pdev->dev;
-	struct resource *res, *irq;
+	struct resource *res;
 	const struct rcar_thermal_chip *chip = of_device_get_match_data(dev);
 	int mres = 0;
 	int i;
@@ -467,9 +467,16 @@ static int rcar_thermal_probe(struct platform_device *pdev)
 	pm_runtime_get_sync(dev);
 
 	for (i = 0; i < chip->nirqs; i++) {
-		irq = platform_get_resource(pdev, IORESOURCE_IRQ, i);
-		if (!irq)
-			continue;
+		int irq;
+
+		ret = platform_get_irq_optional(pdev, i);
+		if (ret < 0 && ret != -ENXIO)
+			goto error_unregister;
+		if (ret > 0)
+			irq = ret;
+		else
+			break;
+
 		if (!common->base) {
 			/*
 			 * platform has IRQ support.
@@ -487,7 +494,7 @@ static int rcar_thermal_probe(struct platform_device *pdev)
 			idle = 0; /* polling delay is not needed */
 		}
 
-		ret = devm_request_irq(dev, irq->start, rcar_thermal_irq,
+		ret = devm_request_irq(dev, irq, rcar_thermal_irq,
 				       IRQF_SHARED, dev_name(dev), common);
 		if (ret) {
 			dev_err(dev, "irq request failed\n ");