[nrf noup] Make fprotect area span only MCUBoot#576

rlubos merged 1 commit intonrfconnect:mainnrfconnect/sdk-mcuboot:mainfrom

ahasztag:NCSIDB-1734_fprotect_boundaries_fixahasztag/sdk-mcuboot:NCSIDB-1734_fprotect_boundaries_fixCopy head branch name to clipboard