export nm_*_name() functions to get operational and availability state to strings

diff --git a/include/openbsc/abis_nm.h b/include/openbsc/abis_nm.h
index c280c89..73bb19c 100644
--- a/include/openbsc/abis_nm.h
+++ b/include/openbsc/abis_nm.h
@@ -569,4 +569,6 @@
 int nm_state_event(enum nm_evt evt, u_int8_t obj_class, void *obj,
 		   struct gsm_nm_state *old_state, struct gsm_nm_state *new_state); 
 
+const char *nm_opstate_name(u_int8_t os);
+const char *nm_avail_name(u_int8_t avail);
 #endif /* _NM_H */