ARM: at91: ma5d4: Switch DDR2 controller to sequencial address decoding

According to the datasheet, sequential mapping is used for DDR
SDRAM, while interleaved mapping is used for regular SDRAM.
Incorrect configuration of this bit does indeed cause sporadic
memory instability.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Andreas Bießmann <andreas.devel@googlemail.com>
Cc: Wenyou Yang <wenyou.yang@atmel.com>