board/ls2081ardb: Update QSPI flash type from n25q512a to s25fs512s

As per updated board design, different QSPI flash
is connected on boards, hence change QSPI flash type
from Micron n25q512a device to spansion s25fs512s
device in dts and config.

Signed-off-by: Santan Kumar <santan.kumar@nxp.com>
Signed-off-by: Yogesh Gaur <yogeshnarayan.gaur@nxp.com>
Signed-off-by: Priyanka Jain <priyanka.jain@nxp.com>
Reviewed-by: York Sun <york.sun@nxp.com>