x86, olpc: Register XO-1 platform devices

The upcoming XO-1 rfkill driver (for drivers/platform/x86) will register
itself with the name "xo1-rfkill", and the already-merged XO-1 poweroff
code uses name "olpc-xo1"

Add the necessary mechanics so that these devices are properly
initialized on XO-1 laptops.

Signed-off-by: Daniel Drake <dsd@laptop.org>
LKML-Reference: <20101013181042.90C8F9D401B@zog.reactivated.net>
Cc: Matthew Garrett <mjg@redhat.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>