powerpc/85xx: Add C293PCIE board support

C293PCIE board is a series of Freescale PCIe add-in cards to perform
as public key crypto accelerator or secure key management module.

 - 512KB platform SRAM in addition to 512K L2 Cache/SRAM
 - 512MB soldered DDR3 32bit memory
 - CPLD System Logic
 - 64MB x16 NOR flash and 4GB x8 NAND flash
 - 16MB SPI flash

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