powerpc/p2041rdb: update cpld reset command according to CPLD 2.0

CPLD 2.0 provides a new register which bit[0] is set to '1' will reset
board with initializing the CPLD registers to default values. And add
bit[6] of register at offset 0x5 to use to enable flash bank selection.

Signed-off-by: Shaohui Xie <Shaohui.Xie@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>