board: corenet_ds: MAINTAINERS: Remove redundant entries

Remove MAINTAINERS entries for
P3041DS_NAND_SECURE_BOOT_defconfig
and P5040DS_NAND_SECURE_BOOT_defconfig
as these configs support have been removed.

Signed-off-by: Priyanka Jain <priyanka.jain@nxp.com>