T: replace 'subframe' by 'tick'

Some code in T tracers is used by both LTE and NR.

In LTE, we expect 10 subframes per frame, and the logging is done with
this assumption. We have one tick per subframe.

In NR, we deal with slots, not subframes. And we have n ticks per frame
(depending on mu). As of today, only n=20 is tested (corresponding to
mu=1).

A previous commit introduced 'subframes_per_frame' which had the correct
meaning for LTE but was truly 'slots per frame' for NR. This creates
confusion.

Let's replace 'subframe' by 'tick' to reduce confusion.

common/utils/T/tracer/logger/logger.h

@@ -15,8 +15,8 @@ logger *new_ticked_ttilog(void *event_handler, void *database,
     char *event_name, char *data_varname,
     int convert_to_dB, float empty_value);
 logger *new_throughputlog(void *event_handler, void *database,
-    char *tick_event_name, char *frame_varname, char *subframe_varname,
-    char *event_name, char *data_varname, int subframes_per_frame);
+    char *tick_event_name, char *frame_varname, char *tick_varname,
+    char *event_name, char *data_varname, int ticks_per_frame);
 logger *new_timelog(void *event_handler, void *database, char *event_name);
 logger *new_ticklog(void *event_handler, void *database,
     char *event_name, char *frame_name, char *subframe_name);