Somewhere around commit 9ff9d9f reserving entire PCI slots was
eliminated, as demonstrated by commit 6cc2014.
Reserve the functions required by the implicit devices:
00:01.0 ISA Bridge
00:01.1 IDE Controller
00:01.2 USB Controller (unless USB is disabled)
00:01.3 Bridge
https://bugzilla.redhat.com/show_bug.cgi?id=1460143
