powerpc/85xx: Add C29x SoC support

The Freescale C29x family is a high performance crypto co-processor.
It combines a single e500v2 core with necessary SEC engine. There're
three SoC types(C291, C292, C293) with the following features:

 - 512K L2 Cache/SRAM and 512 KB platform SRAM
 - DDR3/DDR3L 32bit DDR controller
 - One PCI express (x1, x2, x4) Gen 2.0 Controller
 - Trust Architecture 2.0
 - SEC6.0 engine

Signed-off-by: Mingkai Hu <Mingkai.Hu@freescale.com>
Signed-off-by: Po Liu <Po.Liu@freescale.com>