[POWERPC] 83xx: Add support for Wind River SBC834x boards

This adds the basic support for the Wind River SBC834x boards.  The
SBC8349 is more common, although it should work on the SBC8347 board
as well.  Support is heavily based on the existing MPC834x_MDS code.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>