powerpc/mpc85xx: Add T4160 SoC

T4160 SoC is low power version of T4240. The T4160 combines eight dual
threaded Power Architecture e6500 cores and two memory complexes (CoreNet
platform cache and DDR3 memory controller) with the same high-performance
datapath acceleration, networking, and peripheral bus interfaces.

Signed-off-by: York Sun <yorksun@freescale.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>