drm/exynos: IS_ERR() vs NULL bug

of_iomap() doesn't return error pointers, it returns NULL on error.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/exynos7_drm_decon.c

@@ -888,8 +888,8 @@ static int decon_probe(struct platform_device *pdev)
 	of_node_put(i80_if_timings);
 
 	ctx->regs = of_iomap(dev->of_node, 0);
-	if (IS_ERR(ctx->regs)) {
-		ret = PTR_ERR(ctx->regs);
+	if (!ctx->regs) {
+		ret = -ENOMEM;
 		goto err_del_component;
 	}