PCI: imx: Fix checking pd_pcie_phy device link addition

The check on the device_link_add() return value is wrong;
this leads to erroneous code execution, so fix it.

Fixes: 3f7cceea ("PCI: imx: Add multi-pd support")
Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
[lorenzo.pieralisi@arm.com: updated commit log]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

drivers/pci/controller/dwc/pci-imx6.c

@@ -326,13 +326,13 @@ static int imx6_pcie_attach_pd(struct device *dev)
 	if (IS_ERR(imx6_pcie->pd_pcie_phy))
 		return PTR_ERR(imx6_pcie->pd_pcie_phy);
 
-	device_link_add(dev, imx6_pcie->pd_pcie_phy,
+	link = device_link_add(dev, imx6_pcie->pd_pcie_phy,
 			DL_FLAG_STATELESS |
 			DL_FLAG_PM_RUNTIME |
 			DL_FLAG_RPM_ACTIVE);
-	if (IS_ERR(link)) {
-		dev_err(dev, "Failed to add device_link to pcie_phy pd: %ld\n", PTR_ERR(link));
-		return PTR_ERR(link);
+	if (!link) {
+		dev_err(dev, "Failed to add device_link to pcie_phy pd.\n");
+		return -EINVAL;
 	}
 
 	return 0;