PCI: Get rid of dev->has_secondary_link flag

In some systems, the Device/Port Type in the PCI Express Capabilities
register incorrectly identifies upstream ports as downstream ports.

d0751b98dfa3 ("PCI: Add dev->has_secondary_link to track downstream PCIe
links") addressed this by adding pci_dev.has_secondary_link, which is set
for downstream ports.  But this is confusing because pci_pcie_type()
sometimes gives the wrong answer, and it's not obvious that we should use
pci_dev.has_secondary_link instead.

Reduce the confusion by correcting the type of the port itself so that
pci_pcie_type() returns the actual type regardless of what the Device/Port
Type register claims it is.  Update the users to call pci_pcie_type() and
pcie_downstream_port() accordingly, and remove pci_dev.has_secondary_link
completely.

Link: https://lore.kernel.org/linux-pci/20190703133953.GK128603@google.com/
Suggested-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://lore.kernel.org/r/20190822085553.62697-2-mika.westerberg@linux.intel.com
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
diff --git a/drivers/pci/vc.c b/drivers/pci/vc.c
index 5acd9c0..9ae9fb9 100644
--- a/drivers/pci/vc.c
+++ b/drivers/pci/vc.c
@@ -13,6 +13,8 @@
 #include <linux/pci_regs.h>
 #include <linux/types.h>
 
+#include "pci.h"
+
 /**
  * pci_vc_save_restore_dwords - Save or restore a series of dwords
  * @dev: device
@@ -105,7 +107,7 @@ static void pci_vc_enable(struct pci_dev *dev, int pos, int res)
 	struct pci_dev *link = NULL;
 
 	/* Enable VCs from the downstream device */
-	if (!dev->has_secondary_link)
+	if (!pci_is_pcie(dev) || !pcie_downstream_port(dev))
 		return;
 
 	ctrl_pos = pos + PCI_VC_RES_CTRL + (res * PCI_CAP_VC_PER_VC_SIZEOF);