AT91SAM9260EK: Fix dataflash offsets in CONFIG_BOOTCOMMAND

This patch fixes the dataflash offsets used in CONFIG_BOOTCOMMAND
in order to cope with the changes in DataFlash partitionning scheme
(cset c3a60cb3).

Signed-off-by: Stelian Pop <stelian@popies.net>
Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>