Import patch from xen.git fixing PCI passthrough.

This was patch 28ae1705384b6134c05ddcdb0f7572a92a3ea368

Original commit message:

> tools/ocaml: libxc bindings: Fix SBDF encoding

> Changeset 23861:ec7c81fbe0de alters the SBDF encoding expected by the
> DOMCTL_{de,}assign_device hypercalls.

> While it updates libxl, libxc and the python bindings, the ocaml
> bindings got missed.  As a result, any attempt to use PCI Passthrough
> with Xen-4.2 and later will fail.

> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
> Acked-by: Ian Campbell <ian.campbell@citrix.com>
> Committed-by: Ian Campbell <ian.campbell@citrix.com>
Import patch fixing terminology of PCI passthrough:

Origin patch was d0a831865d1331744217111ccdc2d71f3fc455a2

Original commit message:

> tools/ocaml: libxc bindings: Correct PCI terminology

> Some renaming to correct the PCI and SBDF terminology.

> No functional change.

> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
> Acked-by: Ian Campbell <ian.campbell@citrix.com>
> Committed-by: Ian Campbell <ian.campbell@citrix.com>