Add counters for BSSMAP cipher mode messages

Count COMPLETE and REJECT messages. Besides general troubleshooting
that's also useful for TTCN-3 tests to check that OsmoMSC processed
those messages as expected.

Change-Id: I5822b2b38b64f1a691b26c926a8e2bece21dc624
Related: OS#3187
2 files changed