PCI: dwc: pci-dra7xx: Use devm_platform_ioremap_resource_byname()

platform_get_resource() may fail and return NULL, so we had better
check its return value to avoid a NULL pointer dereference a bit later
in the code. Fix it to use devm_platform_ioremap_resource_byname()
instead of calling platform_get_resource_byname() and devm_ioremap().

Link: https://lore.kernel.org/r/20200429015027.134485-1-weiyongjun1@huawei.comSigned-off-by: Wei Yongjun <weiyongjun1@huawei.com>
[lorenzo.pieralisi@arm.com: commit log]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

drivers/pci/controller/dwc/pci-dra7xx.c

@@ -840,7 +840,6 @@ static int __init dra7xx_pcie_probe(struct platform_device *pdev)
 	struct phy **phy;
 	struct device_link **link;
 	void __iomem *base;
-	struct resource *res;
 	struct dw_pcie *pci;
 	struct dra7xx_pcie *dra7xx;
 	struct device *dev = &pdev->dev;
@@ -877,10 +876,9 @@ static int __init dra7xx_pcie_probe(struct platform_device *pdev)
 		return irq;
 	}
 
-	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "ti_conf");
-	base = devm_ioremap(dev, res->start, resource_size(res));
-	if (!base)
-		return -ENOMEM;
+	base = devm_platform_ioremap_resource_byname(pdev, "ti_conf");
+	if (IS_ERR(base))
+		return PTR_ERR(base);
 
 	phy_count = of_property_count_strings(np, "phy-names");
 	if (phy_count < 0) {