Do not expect all BTSs support TSC != BCC

We introduce a new feature indicating if the given BTS model
supports a TSC that is different from the BCC (lower 3 bits of BSIC).
diff --git a/openbsc/src/libbsc/bts_ipaccess_nanobts.c b/openbsc/src/libbsc/bts_ipaccess_nanobts.c
index dfc8d16..c254127 100644
--- a/openbsc/src/libbsc/bts_ipaccess_nanobts.c
+++ b/openbsc/src/libbsc/bts_ipaccess_nanobts.c
@@ -510,6 +510,7 @@
 
 	gsm_btsmodel_set_feature(&bts_model_nanobts, BTS_FEAT_GPRS);
 	gsm_btsmodel_set_feature(&bts_model_nanobts, BTS_FEAT_EGPRS);
+	gsm_btsmodel_set_feature(&bts_model_nanobts, BTS_FEAT_MULTI_TSC);
 
 	return gsm_bts_model_register(&bts_model_nanobts);
 }