powerpc/86xx: Default configutation for GE Fanuc's SBC310

Support for the SBC310 VPX Single Board Computer from GE Fanuc (PowerPC
MPC8641D).

This is the default config file for GE Fanuc's SBC310, a 3U single board
computer, based on Freescale's MPC8641D.

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