pci: stash device's PXM information in struct pci_dev

pci: stash device's PXM information in struct pci_dev

If ACPI provides PXM data for IO devices then dom0 will pass it to
hypervisor during PHYSDEVOP_pci_device_add call. This information,
however, is currently ignored.

We will store this information (in the form of nodeID) in pci_dev
structure so that we can provide it, for example, to the toolstack
when it adds support (in the following patches) for querying the
hypervisor about device topology

We will also print it when user requests device information dump.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>