The early chipsets cannot safely handle Async Notification (AN),
but 6041/6081 chip revision "C0" (and newer) can handle it.

So allow AN for "C0" and higher.

This enables use of hotplug on PMP ports for the 6041/6081 PCI Rev.9 chips.
Signed-off-by: Mark Lord <mlord@pobox.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>