drm/exynos: gsc: 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: Inki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/exynos_drm_gsc.c

@@ -1220,7 +1220,6 @@ static int gsc_probe(struct platform_device *pdev)
 	struct gsc_driverdata *driver_data;
 	struct exynos_drm_ipp_formats *formats;
 	struct gsc_context *ctx;
-	struct resource *res;
 	int num_formats, ret, i, j;
 
 	ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
@@ -1275,13 +1274,10 @@ static int gsc_probe(struct platform_device *pdev)
 		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;
-	}
+	ctx->irq = platform_get_irq(pdev, 0);
+	if (ctx->irq < 0)
+		return ctx->irq;
 
-	ctx->irq = res->start;
 	ret = devm_request_irq(dev, ctx->irq, gsc_irq_handler, 0,
 			       dev_name(dev), ctx);
 	if (ret < 0) {