x86, amd: Don't probe for extended APIC ID if APICs are disabled

x86, amd: Don't probe for extended APIC ID if APICs are disabled

commit 2cb078603abb612e3bcd428fb8122c3d39e08832 upstream.

If we've logically disabled apics, don't probe the PCI space for the
AMD extended APIC ID.

[ Impact: prevent boot crash under Xen. ]

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Reported-by: Bastian Blank <bastian@waldi.eu.org>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Andreas Herrmann <andreas.herrmann3@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>