powerpc/83xx: Add localbus node and MTD partitions for SBC834x

There is 8MB flash, 8kB EEPROM and 128MB SDRAM on the sbc834x
local bus, so add a localbus node in DTS with MTD partitions.

The recent U-boot commit fe613cdd4eb moves u-boot to the beginning
of flash, hence the legacy label on the partition at the end of flash.

Signed-off-by: Liang Li <liang.li@windriver.com>
Signed-off-by: Yang Shi <yang.shi@windriver.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>