PCI: Add ACS quirk for APM X-Gene devices

The APM X-Gene PCIe root port does not support ACS at this point.  However,
the hardware provides isolation and source validation through the SMMU.
The stream ID generated by the PCIe ports contain both the bus/device/
function number as well as the port ID in its 3 most significant bits.
Turn on ACS but disable all the peer-to-peer features.

Signed-off-by: Feng Kan <fkan@apm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Acked-by: Tanmay Inamdar <tinamdar@apm.com>