Fixes for DATA_MESSAGE_SND

1) Fix the UCI Data Packet header length extracted during fragmentation.
2) Fix the payload data size definition in the Data Message (SND/RCV) packets. It cannot be larger than the size defined in the UCI spec (even for an unfragmented packet).

Test: atest
Bug: 268567239
Change-Id: I274e37d2018348c9570b3eab006274d086988161
2 files changed