powerpc/8xx: Remove Kconfig symbol FADS

Commit 39eb56da ("pcmcia: Remove m8xx_pcmcia driver") removed the
only driver that used CONFIG_FADS. Setting the Kconfig symbol FADS is
pointless since that commit. Remove it.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Scott Wood <scottwood@freescale.com>