Adjust BTS model feature check

Rename gsm_bts_has_feature() -> gsm_btsmodel_has_feature() and adjust
type signature to match gsm_btsmodel_set_feature() function and avoid
confusion with upcoming functions to check/set BTS features reported
over OML.

Change-Id: I97abdedbef568e0c2fbd37c110f7d658cf20e100
Related: OS#1614
diff --git a/openbsc/src/libbsc/bsc_vty.c b/openbsc/src/libbsc/bsc_vty.c
index f17bde6..0ee2390 100644
--- a/openbsc/src/libbsc/bsc_vty.c
+++ b/openbsc/src/libbsc/bsc_vty.c
@@ -3607,7 +3607,7 @@
 {
 	struct gsm_bts_trx_ts *ts = vty->index;
 
-	if (!gsm_bts_has_feature(ts->trx->bts, BTS_FEAT_MULTI_TSC)) {
+	if (!gsm_btsmodel_has_feature(ts->trx->bts->model, BTS_FEAT_MULTI_TSC)) {
 		vty_out(vty, "%% This BTS does not support a TSC != BCC, "
 			"falling back to BCC%s", VTY_NEWLINE);
 		ts->tsc = -1;
@@ -3630,7 +3630,7 @@
 	struct gsm_bts_trx_ts *ts = vty->index;
 	int enabled = atoi(argv[0]);
 
-	if (enabled && !gsm_bts_has_feature(ts->trx->bts, BTS_FEAT_HOPPING)) {
+	if (enabled && !gsm_btsmodel_has_feature(ts->trx->bts->model, BTS_FEAT_HOPPING)) {
 		vty_out(vty, "BTS model does not support hopping%s",
 			VTY_NEWLINE);
 		return CMD_WARNING;