Add board enable for abit BF6.

Because the board does not have any PCI subsystem IDs set and the
DMI strings are not very specific at all, autodetection has been disabled.
The GPIO was found by roxfan and the patch tested on hardware by Gelip,
thanks!

Signed-off-by: Stefan Tauner <stefan.tauner@student.tuwien.ac.at>
Acked-by: Stefan Tauner <stefan.tauner@student.tuwien.ac.at>

git-svn-id: svn://flashrom.org/flashrom/trunk@1762 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1