abis_nm: Some more fall-out from the abis_nm move to libosmocore

we want get_string_value(), not the equivalent of get_value_string()
diff --git a/openbsc/src/libbsc/abis_nm_vty.c b/openbsc/src/libbsc/abis_nm_vty.c
index d043c35..3a16b2b 100644
--- a/openbsc/src/libbsc/abis_nm_vty.c
+++ b/openbsc/src/libbsc/abis_nm_vty.c
@@ -86,7 +86,7 @@
 		return CMD_WARNING;
 
 	oms->bts = bts;
-	oms->obj_class = abis_nm_obj_class_name(argv[1]);
+	oms->obj_class = get_string_value(abis_nm_obj_class_names, argv[1]);
 	oms->obj_inst[0] = atoi(argv[2]);
 	oms->obj_inst[1] = atoi(argv[3]);
 	oms->obj_inst[2] = atoi(argv[4]);
@@ -161,7 +161,7 @@
 	struct oml_node_state *oms = vty->index;
 	enum abis_nm_adm_state state;
 
-	state = abis_nm_adm_state_name(argv[0]);
+	state = get_string_value(abis_nm_adm_state_names, argv[0]);
 
 	abis_nm_chg_adm_state(oms->bts, oms->obj_class, oms->obj_inst[0],
 			      oms->obj_inst[1], oms->obj_inst[2], state);