CPUID emulation presented Intel topology information to the guest, but
disabled AMD topology information and in some cases passed through
garbage. (I.e., 8000_001[de] were passed through to the guest, but
guest threads can migrate between host cores and threads, so the
information presented was not consistent).
Slightly improve this situation by enabling AMD topology feature flag
and presenting at least the CPUID fields used by FreeBSD itself to probe
topology on more modern AMD64 hardware (Family 15h+). Older stuff is
probably less interesting.