mgmt: add Mtu to faces/create and FaceStatus

refs #4005

Change-Id: I26c02aa088dc59aecd331cd579036177fef0f64c
diff --git a/src/encoding/tlv-nfd.hpp b/src/encoding/tlv-nfd.hpp
index 12ef55b..dcaed7e 100644
--- a/src/encoding/tlv-nfd.hpp
+++ b/src/encoding/tlv-nfd.hpp
@@ -69,6 +69,7 @@
   LinkType                      = 134,
   BaseCongestionMarkingInterval = 135,
   DefaultCongestionThreshold    = 136,
+  Mtu                           = 137,
   FaceQueryFilter               = 150,
   FaceEventNotification         = 192,
   FaceEventKind                 = 193,