freetdm: no need for hw dtmf events on startup

libs/freetdm/src/ftmod/ftmod_wanpipe/ftmod_wanpipe.c

@@ -274,13 +274,10 @@ static unsigned wp_open_range(ftdm_span_t *span, unsigned spanno, unsigned start
 
 				err = sangoma_tdm_get_hw_dtmf(chan->sockfd, &tdm_api);
 				if (err > 0) {
-					err = sangoma_tdm_enable_dtmf_events(chan->sockfd, &tdm_api);
-					if (err == 0) {
 					ftdm_channel_set_feature(chan, FTDM_CHANNEL_FEATURE_DTMF_DETECT);
 					dtmf = "hardware";
 				}
 			}
-			}
 
 #ifdef LIBSANGOMA_VERSION
 			if (type == FTDM_CHAN_TYPE_FXS) {