Fix Geode GX2 + LX caching for tiny bootblock.

Fix Geode GX2 + LX caching for tiny bootblock.

Change-Id: If681a33deb7df752b37c6a8a20482d3c374af936
Signed-off-by: Nils Jacobs <njacobs8@adsltotaal.nl>
Reviewed-on: http://review.coreboot.org/528
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>
Reviewed-by: Philip Prindeville <philipp@redfish-solutions.com>