ctdb: Fixing memory leak in ctdb_tcp_tnode_cb

It is expected by the caller(queue_process) that the callback is
free'ing the memory referenced by the data pointer.

Signed-off-by: Swen Schillig <swen@vnet.ibm.com>
Reviewed-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Jeremy Allison <jra@samba.org>
