properly reset the MO state of all MO on Abis disconnect

When we loose the A-bis link, we should properly re-set the
administrative, operational and availability state of all MOs
diff --git a/openbsc/src/libbsc/bsc_init.c b/openbsc/src/libbsc/bsc_init.c
index 8654dd7..1be8cb7 100644
--- a/openbsc/src/libbsc/bsc_init.c
+++ b/openbsc/src/libbsc/bsc_init.c
@@ -292,15 +292,9 @@
 					lchan_free(&ts->lchan[lchan_no]);
 				lchan_reset(&ts->lchan[lchan_no]);
 			}
-
-			ts->mo.nm_state.operational = 0;
-			ts->mo.nm_state.availability = 0;
 		}
 
-		trx->mo.nm_state.operational = 0;
-		trx->mo.nm_state.availability = 0;
-		trx->bb_transc.mo.nm_state.operational = 0;
-		trx->bb_transc.mo.nm_state.availability = 0;
+		gsm_bts_mo_reset(trx->bts);
 
 		abis_nm_clear_queue(trx->bts);
 		break;