Move TBF list from BTS to the TRX structure

The TBFs are managed per TRX. Move the global list from BTS to TRX.

Related: OS#1541
Change-Id: Id3c59c11d57d765fe68aaebaac94290c0d84feb2
diff --git a/src/tbf_dl.cpp b/src/tbf_dl.cpp
index 27dc4cf..45856e8 100644
--- a/src/tbf_dl.cpp
+++ b/src/tbf_dl.cpp
@@ -168,7 +168,7 @@
 		}
 	}
 
-	llist_add(tbf_bts_list((struct gprs_rlcmac_tbf *)tbf), &bts->dl_tbfs);
+	llist_add(tbf_trx_list((struct gprs_rlcmac_tbf *)tbf), &tbf->trx->dl_tbfs);
 	bts_do_rate_ctr_inc(tbf->bts, CTR_TBF_DL_ALLOCATED);
 
 	osmo_clock_gettime(CLOCK_MONOTONIC, &tbf->m_bw.dl_bw_tv);