command: correct the normal case when shutdown

    We could directly return when all processes are down.
    That is a normal case, we should not see the following error
    log out of the for-loop.

Signed-off-by: Vicente Cheng <vicente.cheng@suse.com>

app/cmd/start.go

@@ -88,7 +88,7 @@ func cleanup(pm *process.Manager) {
 		}
 		if len(pmResp.Processes) == 0 {
 			logrus.Info("Shutdown all instance processes successfully")
-			break
+			return
 		}
 		time.Sleep(types.WaitInterval)
 	}