powerpc/85xx: enable some P1/P2 boards mtdparts for nor flash

Enable these boards mtdparts for nor flash:
p1020rdb-pd, p1021rdb-pc, p1022ds, p1025twr, and p2020rdb-pc.

Signed-off-by: Xie Xiaobo <X.Xie@freescale.com>
Signed-off-by: Yangbo Lu <yangbo.lu@freescale.com>
Cc: York Sun <yorksun@freescale.com>
Cc: Scott Wood <scottwood@freescale.com>