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/tbf_ul_ass_fsm.c b/src/tbf_ul_ass_fsm.c
index 00f4bfd..eab34ee 100644
--- a/src/tbf_ul_ass_fsm.c
+++ b/src/tbf_ul_ass_fsm.c
@@ -127,6 +127,8 @@
 	bts_do_rate_ctr_inc(ms->bts, CTR_PKT_UL_ASSIGNMENT);
 
 	tbf_set_polling(ctx->tbf, new_poll_fn, d->ts, PDCH_ULC_POLL_UL_ASS);
+	LOGPTBFDL(ctx->tbf, LOGL_INFO, "Scheduled UL Assignment polling on PACCH (FN=%d, TS=%d)\n",
+		  new_poll_fn, d->ts);
 
 	talloc_free(mac_control_block);
 	return msg;