Handle GenerateTimestampToken messages on the host side.

Bug: 182928606
Test: N/A
Change-Id: I54a8201452479c83c35a3f8df5de73644cd03480
diff --git a/host/commands/secure_env/keymaster_responder.cpp b/host/commands/secure_env/keymaster_responder.cpp
index 013d5e7..a564254 100644
--- a/host/commands/secure_env/keymaster_responder.cpp
+++ b/host/commands/secure_env/keymaster_responder.cpp
@@ -65,6 +65,7 @@
     HANDLE_MESSAGE(DELETE_KEY, DeleteKey)
     HANDLE_MESSAGE(DELETE_ALL_KEYS, DeleteAllKeys)
     HANDLE_MESSAGE(IMPORT_WRAPPED_KEY, ImportWrappedKey)
+    HANDLE_MESSAGE(GENERATE_TIMESTAMP_TOKEN, GenerateTimestampToken)
 #undef HANDLE_MESSAGE
 #define HANDLE_MESSAGE_W_RETURN(ENUM_NAME, METHOD_NAME) \
     case ENUM_NAME: {\