powerpc/86xx: Update GE Fanuc sbc310 default configuration

General update of defconfig including the following notable changes:
 - Enable Highmem support.
 - Support for PCMCIA based daughter card.

Signed-off-by: Martyn Welch <martyn.welch@gefanuc.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>