powerpc/mpc85xx: Add new ext fields to Integrated FLash Controller

Freescale's Integrated Flash controller(IFC) v1.1.0 supports 40 bit
address bus width.
In case more than 32 bit address is used, the EXT registers should be set.

Add support of ext registers.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: York Sun <yorksun@freescale.com>
Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>