drm/exynos/fimc: 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 <[e-mail]>
Signed-off-by: Inki Dae <[e-mail]>

drivers/gpu/drm/exynos/exynos_drm_fimc.c

···
 	struct exynos_drm_ipp_formats *formats;
 	struct device *dev = &pdev->dev;
 	struct fimc_context *ctx;
-	struct resource *res;
 	int ret;
 	int i, j, num_limits, num_formats;
 
···
 		return PTR_ERR(ctx->regs);
 
 	/* resource irq */
-	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
-	if (!res) {
-		dev_err(dev, "failed to request irq resource.\n");
-		return -ENOENT;
-	}
+	ret = platform_get_irq(pdev, 0);
+	if (ret < 0)
+		return ret;
 
-	ret = devm_request_irq(dev, res->start, fimc_irq_handler,
-		0, dev_name(dev), ctx);
+	ret = devm_request_irq(dev, ret, fimc_irq_handler,
+			       0, dev_name(dev), ctx);
 	if (ret < 0) {
 		dev_err(dev, "failed to request irq.\n");
 		return ret;