85xx/p1_p2_rdb: Added RevD board version support

- Also modified the code to use io accessors.

Signed-off-by: Poonam Aggrwal <poonam.aggrwal@freescale.com>
Signed-off-by: Dipen Dudhat <dipen.dudhat@freescale.com>
Acked-by: Kumar Gala <galak@kernel.crashing.org>