Simplify tbf::set_polling()

When setting a POLL, it will always happen on PACCH, so all the CCCH
part makes no sense there. Let's drop it and move the logging of each
case to the caller, where logging file+line is more useful.

Change-Id: I242f97fd6f927131ac64c1a7c9c3812b6389de04
diff --git a/src/nacc_fsm.c b/src/nacc_fsm.c
index 9a5f5b5..738b2c5 100644
--- a/src/nacc_fsm.c
+++ b/src/nacc_fsm.c
@@ -207,6 +207,8 @@
 	rate_ctr_inc(rate_ctr_group_get_ctr(bts_rate_counters(ms->bts), CTR_PKT_CELL_CHG_CONTINUE));
 	talloc_free(mac_control_block);
 	tbf_set_polling(tbf, *new_poll_fn, data->ts, PDCH_ULC_POLL_CELL_CHG_CONTINUE);
+	LOGPTBFDL(tbf, LOGL_DEBUG, "Scheduled 'Packet Cell Change Continue' polling on PACCH (FN=%d, TS=%d)\n",
+		  *new_poll_fn, data->ts);
 	return msg;
 
 free_ret: