SECURE_BOOT: Update bootscript and its hdr addresses

Update bootscript and its hdr addresses for Layerscape Chasis 3
based platforms instead of individual SoCs.

Signed-off-by: Sumit Garg <sumit.garg@nxp.com>
Signed-off-by: Udit Agarwal <udit.agarwal@nxp.com>
Reviewed-by: York Sun <york.sun@nxp.com>