PCI: altera: Check link status before retrain link

Check the link status before retraining.  If the link is not up, don't
bother trying to retrain it.

[bhelgaas: split code move to separate patch, changelog]
Signed-off-by: Ley Foon Tan <lftan@altera.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/host/pcie-altera.c

@@ -100,6 +100,10 @@ static bool altera_pcie_link_is_up(struct altera_pcie *pcie)
 static void altera_pcie_retrain(struct pci_dev *dev)
 {
 	u16 linkcap, linkstat;
+	struct altera_pcie *pcie = dev->bus->sysdata;
+
+	if (!altera_pcie_link_is_up(pcie))
+		return;
 
 	/*
 	 * Set the retrain bit if the PCIe rootport support > 2.5GB/s, but