mgmt: fix conflicting TLV-TYPE assignment

Amends df5053824fc53eec6847067faa2da8b0ebb69917

Change-Id: Ifba9fcac63528594c6442973adce313a95116c75
Refs: #4318, #4538
diff --git a/src/encoding/tlv-nfd.hpp b/src/encoding/tlv-nfd.hpp
index 1c4d12d..12ef55b 100644
--- a/src/encoding/tlv-nfd.hpp
+++ b/src/encoding/tlv-nfd.hpp
@@ -38,6 +38,7 @@
   Origin              = 111,
   Cost                = 106,
   Capacity            = 131,
+  Count               = 132,
   Flags               = 108,
   Mask                = 112,
   Strategy            = 107,