Fixing alarms in poweron/shutdown and added events for flow

Change-Id: Id21128dc0a46f3efd1247e5339d7b2f9cba4c580
diff --git a/internal/bbsim/devices/olt.go b/internal/bbsim/devices/olt.go
index 0209b88..572507e 100644
--- a/internal/bbsim/devices/olt.go
+++ b/internal/bbsim/devices/olt.go
@@ -963,6 +963,10 @@
 		}
 		if !o.enablePerf {
 			onu.Flows = append(onu.Flows, flowKey)
+			// Generate event on first flow for ONU
+			if len(onu.Flows) == 1 {
+				publishEvent("Flow-add-received", int32(onu.PonPortID), int32(onu.ID), onuSnToString(onu.SerialNumber))
+			}
 		}
 
 		msg := Message{
@@ -1012,6 +1016,7 @@
 				return new(openolt.Empty), nil
 			}
 			onu.DeleteFlow(flowKey)
+			publishEvent("Flow-remove-received", int32(onu.PonPortID), int32(onu.ID), onuSnToString(onu.SerialNumber))
 		}
 
 		// delete from olt flows