powerpc/85xx: Add support for SMP initialization

Added 85xx specifc smp_ops structure.  We use ePAPR style boot release
and the MPIC for IPIs at this point.

Additionally added routines for secondary cpu entry and initializtion.

Signed-off-by: Andy Fleming <afleming@freescale.com>
Signed-off-by: Trent Piepho <tpiepho@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>