PCI: xgene: Fix the xgene_msi_probe() return code

If devm_ioremap_resource() detects an error condition in the return
value through IS_ERR(), the return value should be retrieved through
PTR_ERR() instead of hardcoding it.

Fix the xgene_msi_probe() error return code.
Signed-off-by: Fabio Estevam <festevam@gmail.com>
[lorenzo.pieralisi@arm.com: rewrote commit log]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

drivers/pci/host/pci-xgene-msi.c

@@ -456,7 +456,7 @@ static int xgene_msi_probe(struct platform_device *pdev)
 	xgene_msi->msi_regs = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(xgene_msi->msi_regs)) {
 		dev_err(&pdev->dev, "no reg space\n");
-		rc = -EINVAL;
+		rc = PTR_ERR(xgene_msi->msi_regs);
 		goto error;
 	}
 	xgene_msi->msi_addr = res->start;