[POWERPC] 85xx: Add v1 device tree source for Wind River SBC8560 board

This adds a v1 device tree source for the Wind River SBC8560 board.  The
biggest difference between this and the MPC8560ADS reference platform
dts is the use of an external 16550 compatible UART instead of the CPM2.

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