bugfix: fix timing advance
- remove global variables in the function lte_est_timing_advance_pusch - do the smoothing logic that was in lte_est_timing_advance_pusch in rx_sdu (is it necessary? is it correct?) - put back the value 100 in prach_procedures for the test on prach energy - change the value of timing_advance_update it was: timing_advance_update = sync_pos - eNB->frame_parms.nb_prefix_samples/4; //to check it is now: timing_advance_update = sync_pos; // - eNB->frame_parms.nb_prefix_samples/4; //to check this should be checked somehow. The computation looked suspicious. Maybe the new one is wrong.