Add emulation of aCube Sam460ex board based on AMCC 460EX embedded SoC.
This is not a complete implementation yet with a lot of components
still missing but enough for the U-Boot firmware to start and to boot
a Linux kernel or AROS.

Signed-off-by: François Revol <revol@free.fr>
Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>