face: Fixing a small bug

Change-Id: I02d6e5de2046a9cf4c9ab00a309609dfa26f6dfb
diff --git a/daemon/face/face.cpp b/daemon/face/face.cpp
index 9c8613b..d0bde55 100644
--- a/daemon/face/face.cpp
+++ b/daemon/face/face.cpp
@@ -23,7 +23,8 @@
   return m_id;
 }
 
-FaceId
+// this method is private and should be used only by the Forwarder
+void
 Face::setId(FaceId faceId)
 {
   m_id = faceId;