p1020rdb-pd: platform support

Add new board p1020RDB-PD. P1020RDB-PD board was update from P1020RDB.
DDR changed from DDR2 1G to DDR3 2G.
NAND: 128 MiB
Flash: 64 MiB

Also change P1020RDB to P1020RDB-PC to distinguish from P1020RDB board.

Signed-off-by: Jerry Huang <Chang-Ming.Huang@freescale.com>
Signed-off-by: Haijun Zhang <Haijun.Zhang@freescale.com>
CC: Scott Wood <scottwood@freescale.com>
Acked-by: York Sun <yorksun@freescale.com>