powerpc: Board support for GE Fanuc SBC610

Support for the SBC610 VPX Single Board Computer from GE Fanuc (PowerPC
MPC8641D).

This is the basic board support for GE Fanuc's SBC610, a 6U 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>