VOL-2367: Lack of ONU Down Indication breaks onu reboot/fiber disconnect

- Use BCMOLT_ONU_AUTO_SUBGROUP_ONU_ACTIVATION_COMPLETED and
  BCMOLT_ONU_AUTO_SUBGROUP_ONU_DEACTIVATION_COMPLETED messages for
  determining onu oper_status "up" and "down" respectively per BAL3.1.

Change-Id: I0332de9dee456415233e803fd0e42302b7117229
diff --git a/agent/src/translation.cc b/agent/src/translation.cc
index 19e9f66..bd41b61 100644
--- a/agent/src/translation.cc
+++ b/agent/src/translation.cc
@@ -40,3 +40,14 @@
     return "unknown";
 }
 
+std::string bcmolt_result_to_string(bcmolt_result result) {
+    switch (result) {
+        case BCMOLT_RESULT_SUCCESS:
+            return "success";
+        case BCMOLT_RESULT_FAIL:
+            return "fail";
+        default:
+            return "unknown";
+    }
+}
+