Add independent updates for security part and non-security part in MCUBoot,as well as can verify and update S&NS together.
This feature is implemented by adding definition TFM_SEGREGATE similar to BL2 in file ConfigRegression.cmake
there are six part In part_map[] :slot0_s\slot0_ns\slot1_s\slot1_ns\scratch_s\scratch_ns.
MCUboot first check and update secure part,then do the same operation to unsecure part.