add a non-standard 0 value failure reason

protocol/esta/acn/dmp/dmp.h

@@ -186,6 +186,7 @@ private:
  * @brief 7 Response Messages
  */
 enum failure_reason {
+  SUCCESS      = 0, //!< The opposite of failure.  Non-standard!
   NONSPECIFIC  = 1, //!< Non-specific or non-DMP reason.
   NOT_PROPERTY = 2, //!< The address does not correspond to a property.
   WRITE_ONLY   = 3, //!< The property’s value may not be read.