powerpc/85xx: Add p2040 RDB board support

powerpc/85xx: Add p2040 RDB board support

P2040RDB Specification:
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2Gbyte unbuffered DDR3 SDRAM SO-DIMM(64bit bus)
128 Mbyte NOR flash single-chip memory
256 Kbit M24256 I2C EEPROM
16 Mbyte SPI memory
SD connector to interface with the SD memory card
dTSEC1: connected to the Vitesse SGMII PHY (VSC8221)
dTSEC2: connected to the Vitesse SGMII PHY (VSC8221)
dTSEC3: connected to the Vitesse SGMII PHY (VSC8221)
dTSEC4: connected to the Vitesse RGMII PHY (VSC8641)
dTSEC5: connected to the Vitesse RGMII PHY (VSC8641)
I2C1: Real time clock, Temperature sensor
I2C2: Vcore Regulator, 256Kbit I2C Bus EEPROM
SATA: Lanes C and Land D of Bank2 are connected to two SATA connectors
UART: supports two UARTs up to 115200 bps for console
USB 2.0: connected via a internal UTMI PHY to two TYPE-A interfaces
PCIe:
 - Lanes E, F, G and H of Bank1 are connected to one x4 PCIe SLOT1
 - Lanes C and Land D of Bank2 are connected to one x4 PCIe SLOT2

Signed-off-by: Mingkai Hu <Mingkai.hu@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>