target-i386: do not override nr_cores for -cpu host

Commit 787aaf5 (target-i386: forward CPUID cache leaves when -cpu host is
used, 2013-09-02) brings bits 31..26 of CPUID leaf 04h out of sync with
the APIC IDs that QEMU reserves for each package.  This number must come
from "-smp" options rather than from the host CPUID.

It also turns out that this unsyncing makes Windows Server 2012R2 fail
to boot.

Tested-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Benoit Canet <benoit@irqsave.net>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Message-id: 1384879786-6721-1-git-send-email-pbonzini@redhat.com
Signed-off-by: Anthony Liguori <aliguori@amazon.com>
