Fix the detection for the Winbond W83697SF. Unfortunately the revision

Fix the detection for the Winbond W83697SF. Unfortunately the revision
has a slightly different format than that of the W83697UF/UG so we have
to hack around it a bit.

This patch has been verified to work on real hardware by
Idwer Vollering <idwer_v@hotmail.com> on IRC (thanks!).

Signed-off-by: Uwe Hermann <uwe@hermann-uwe.de>
Acked-by: Ronald G. Minnich <rminnich@gmail.com>
git-svn-id: svn://svn.coreboot.org/coreboot/trunk@2861 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1