Followup to r1532866: remove a pointless cast dance now that we're not shoving
the kind value in a void pointer.

* subversion/libsvn_repos/dump.c
  (deserialize_node_kind): Both values are already voids.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1532944 13f79535-47bb-0310-9956-ffa450edef68