Fix MS TO measurement representation

* set proper flag when saving MS Timing Offset
* use gsm_subscriber's IMSI or lchan's name if bsc_subscriber is unknown
* add comments with spec reference
* store/display MS Timing Offset instead of raw Timing Offset field from
  RSL
* Compute MS Timing Offset [-63; 192] from Timing Offset field [0; 255],
  adjust structure gsm_meas_rep with proper type to store it

Change-Id: I7e003d23a6edb714c5f17688fd6a8edac131161d
Related: OS#1574
diff --git a/openbsc/src/utils/meas_db.c b/openbsc/src/utils/meas_db.c
index a3b694e..d81efca 100644
--- a/openbsc/src/utils/meas_db.c
+++ b/openbsc/src/utils/meas_db.c
@@ -114,8 +114,7 @@
 	SCK_OK(st->db, sqlite3_bind_int(st->stmt_ins_mr, 6, mr->bs_power));
 
 	if (mr->flags & MEAS_REP_F_MS_TO)
-		SCK_OK(st->db, sqlite3_bind_int(st->stmt_ins_mr, 7,
-						mr->ms_timing_offset));
+		SCK_OK(st->db, sqlite3_bind_int(st->stmt_ins_mr, 7, mr->ms_timing_offset));
 	else
 		SCK_OK(st->db, sqlite3_bind_null(st->stmt_ins_mr, 7));