stmmac: fix ptr_ret.cocci warning

drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c:304:1-3: WARNING: PTR_ERR_OR_ZERO can be used

Use PTR_ERR_OR_ZERO rather than if(IS_ERR(...)) + PTR_ERR

Generated by: scripts/coccinelle/api/ptr_ret.cocci
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
[je: rebase and insert newline before return]
Signed-off-by: Joachim Eastwood <manabian@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c

@@ -298,10 +298,8 @@ int stmmac_get_platform_resources(struct platform_device *pdev,
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	stmmac_res->addr = devm_ioremap_resource(&pdev->dev, res);
-	if (IS_ERR(stmmac_res->addr))
-		return PTR_ERR(stmmac_res->addr);
 
-	return 0;
+	return PTR_ERR_OR_ZERO(stmmac_res->addr);
 }
 EXPORT_SYMBOL_GPL(stmmac_get_platform_resources);