x86/cpuid: Fix booting on AMD Phenom 6-core platform

x86/cpuid: Fix booting on AMD Phenom 6-core platform

c/s 5cecf60f4 "x86/cpuid: Handle leaf 0x1 in guest_cpuid()" causes Linux 4.10
to crash during boot.

It turns out to be because of the reported apic_id, which was altered to be
more consistent across guests.  Revert back to the previous behaviour, by
limiting the apic_id adjustment to HVM guests only.  Whomever gets to fixes
topology representation is going to have a lot of fun with non-power-of-2 AMD
boxes.

Reported-by: Sander Eikelenboom <linux@eikelenboom.it>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Tested-by: Sander Eikelenboom <linux@eikelenboom.it>