[POWERPC] 83xx: Add device tree source for Wind River SBC834x board.

This adds the device tree source for the Wind River SBC834x board.
It is based on the MPC834x_MDS DTS, with the biggest difference being
the lack of BCSR and the PCI2 that the MDS gets via the PIB. That,
and this file is also dts-v1 format.

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