PCI: added some missing subclasses definitions

* also renamed the HT capability mask
PCI: added a HyperTransport mapping info for x86

* fill it with HT MSI mapping capability information.
* enable/disable mapping on the device accordingly in enable_msi(),
disable_msi(), enable_msix(), disable_msix().
* untested. The mapping could instead be enabled/disabled on the HT PCI bus,
aka the parent device of the device passed to enable_msi/disable_msix().