[child-table] enhance address iterator method (#6118)
[child-table] enhance address iterator method (#6118)

Moving the if statement out of the loop always brings the same result.
srickardti/openthread,jwhui/openthread,abtink/openthread,jwhui/openthread,jwhui/openthread,abtink/openthread,jwhui/openthread,openthread/openthread,openthread/openthread,abtink/openthread,openthread/openthread,openthread/openthread,abtink/openthread,srickardti/openthread,srickardti/openthread,srickardti/openthread