armv8: layerscape: Allocate 66 MB DDR for secure memory

Change DDR allocated for secure memory from 2 MB to 66 MB. This
additional 64 MB secure memory is required for trusted OS running
in Trusted Execution Environment using ARMv8 TrustZone.

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