x86, olpc: Only enable PCI configuration type override on XO-1

This configuration type override is for XO-1 only and must not happen
on XO-1.5.

Signed-off-by: Daniel Drake <dsd@laptop.org>
LKML-Reference: <20100923162805.0F6549D401B@zog.reactivated.net>
Cc: Andres Solomon <dilinger@queued.net>
Cc: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>