powerpc/85xx: Add T4240RDB board support

T4240RDB board Specification
----------------------------
Memory subsystem:
     6GB DDR3
     128MB NOR flash
     2GB NAND flash
Ethernet:
     Eight 1G SGMII ports
     Four 10Gbps SFP+ ports
PCIe:
     Two PCIe slots
USB:
     Two USB2.0 Type A ports
SDHC:
     One SD-card port
SATA:
     One SATA port
UART:
     Dual RJ45 ports

Signed-off-by: Chunhe Lan <Chunhe.Lan@freescale.com>
Cc: Scott Wood <scottwood@freescale.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>