km: fixed typo in KM Kirkwood header file

A typo in the km_kirkwood.h header prevented to undefine the initialization
of the Kirkwood PCIe interface.

Signed-off-by: Pascal Linder <pascal.linder@edu.hefr.ch>
Signed-off-by: Holger Brunck <holger.brunck@ch.abb.com>
Signed-off-by: Stefan Roese <sr@denx.de>