follow specification and do not provide PCIe capability.
Verify if the port above such bridge is downstream PCIe (or root port)
and treat the bridge as PCIe/PCI then. This allows to avoid
maintaining the table of device ids for bridges without capability,
while still calculate correct request originator for devices behind
the bridge.
Submitted by: Jason Harmening <jason.harmening@gmail.com>
MFC after: 1 week
af02586229