The config option has been removed by one of the syncs with the Linux
mainline MTD subsystem:
ff94bc40

 (mtd, ubi, ubifs: resync with Linux-3.14)
It has been left inside the config files. Currently does not look to
serve any purpose, so remove it now from all the configs.

Signed-off-by: Igor Grinberg <grinberg@compulab.co.il>
Cc: Matthias Fuchs <matthias.fuchs@esd-electronics.com>
Cc: Stefan Roese <sr@denx.de>
Cc: "Albert ARIBAUD (3ADEV)" <albert.aribaud@3adev.fr>
Cc: Peter Barada <peter.barada@logicpd.com>
Cc: Steve Sakoman <sakoman@gmail.com>
Cc: Peter Tyser <ptyser@xes-inc.com>
Cc: Joe Hershberger <joe.hershberger@ni.com>
Cc: Simon Glass <sjg@chromium.org>
Acked-by: Stefan Roese <sr@denx.de>