armv8: ls1043aqds: modify the qspi_bootcmd definition

Fix the kernel offset of qspi_bootcmd scripts, followed
the qoriq_memory_layout definition.

Signed-off-by: Wen He <wen.he_1@nxp.com>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>