powerpc/85xx: add board support for the Freescale hypervisor

Add support for the ePAPR-compliant Freescale hypervisor (aka "Topaz") on
the Freescale P3041DS, P4080DS, and P5020DS reference boards.

Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>