powerpc/40x: AMCC PowerPC 405EZ Acadia DTS

Add the base DTS for the AMCC PowerPC 405EZ Acadia evalution board.
In addition to some of the normal PPC 40x peripherals, the Acadia
board has:
- 64 MiB PSRAM
- NOR and NAND flash
- Two USB 1.1 host ports
- Two CAN 2.0 ports
- ADC and DAC connectors
- LCD display

This adds the basic platform support to build from.

Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>