PCI: Fix PCI Express Capability accessors for PCI_EXP_FLAGS

PCI_EXP_FLAGS_TYPE is a mask, not an offset.  Fix it.

Previously, pcie_capability_read_word(..., PCI_EXP_FLAGS, ...) would
fail.

[bhelgaas:  tweak changelog]
Signed-off-by: NAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
CC: stable@vger.kernel.org	# v3.7+

drivers/pci/access.c

@@ -515,7 +515,7 @@ static bool pcie_capability_reg_implemented(struct pci_dev *dev, int pos)
 		return false;
 
 	switch (pos) {
-	case PCI_EXP_FLAGS_TYPE:
+	case PCI_EXP_FLAGS:
 		return true;
 	case PCI_EXP_DEVCAP:
 	case PCI_EXP_DEVCTL: