powerpc/c29xpcie: add support for C29XPCIE board

C29XPCIE board is a series of Freescale PCIe add-in cards to perform
as public key crypto accelerator or secure key management module. It
includes C293PCIE board, C293PCIE board and C291PCIE board.

 - 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>
Singed-off-by: Po Liu <Po.Liu@freescale.com>
[yorksun: Fixup include/configs/C29XPCIE.h]
Signed-off-by: York Sun <yorksun@freescale.com>