PCI: Clarify PCI_EXP_TYPE_PCI_BRIDGE comment
PCI: Clarify PCI_EXP_TYPE_PCI_BRIDGE comment

The PCI_EXP_TYPE_PCI_BRIDGE is a *PCIe* function that is a bridge to
PCI/PCI-X.  See PCIe spec r3.0, sec 7.8.2.

Signed-off-by: Bjorn Helgaas <f10ec01be0c6b54271af5c550cd257810bdf3268@google.com>
KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs