[PATCH] libpayload: Bail if the keyboard controller isn't there

[PATCH] libpayload:  Bail if the keyboard controller isn't there

If the system in question does not have a superIO, then a read of
0x64 will return 0xFF and we will loop forever.

Signed-off-by: Jordan Crouse <jordan.crouse@amd.com>
Acked-by: Patrick Georgi <patrick.georgi@coresystems.de>
git-svn-id: svn://svn.coreboot.org/coreboot/trunk@3675 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1