PCI: rcar: Fix rcar_pci_probe() return value check

In case of error, the function devm_ioremap_resource() returns ERR_PTR()
and never returns NULL.  The NULL test in the return value check should
be replaced with IS_ERR().
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Jingoo Han <jg1.han@samsung.com>

drivers/pci/host/pci-rcar-gen2.c

@@ -276,8 +276,8 @@ static int __init rcar_pci_probe(struct platform_device *pdev)
 
 	cfg_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	reg = devm_ioremap_resource(&pdev->dev, cfg_res);
-	if (!reg)
-		return -ENODEV;
+	if (IS_ERR(reg))
+		return PTR_ERR(reg);
 
 	mem_res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
 	if (!mem_res || !mem_res->start)