tz_context.c should be compiled only for secure world,
definition of API's in tz_context.h should be part of secure
binary/bootloader when building mbed-os as non-secure
(Cherry picked from d0a43b8af0)
tz_context.c should be compiled only for secure world,
definition of API's in tz_context.h should be part of secure
binary/bootloader when building mbed-os as non-secure
TZ_context functions are part of secure state binary and are used to handle
secure stack for thread execution.Template implementation from CMSIS is used,
can be enhanced in future.