powerpc/85xx: Add dts for p1020rdb-pc board

P1020RDB-PC Overview
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1Gbyte DDR3 SDRAM
32 Mbyte NAND flash
10 16Mbyte NOR flash
16 Mbyte SPI flash
SD connector to interface with the SD memory card
Real-time clock on I2C bus

PCIe:
- x1 PCIe slot
- x1 mini-PCIe slot

10/100/1000 BaseT Ethernet ports:
- eTSEC1, RGMII: one 10/100/1000 port using VitesseTM VSC7385 L2 switch
- eTSEC2, SGMII: one 10/100/1000 port using VitesseTM VSC8221
- eTSEC3, RGMII: one 10/100/1000 port using AtherosTM AR8021

USB 2.0 port:
- Two USB2.0 Type A receptacles
- One USB2.0 signal to Mini PCIe slot

Dual RJ45 UART ports:
- DUART interface: supports two UARTs up to 115200 bps for console display

Signed-off-by: Zhicheng Fan <b32736@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>