dpif-netdev: Fix memory leak in dpif_netdev_flow_put()

miniflow_destroy() needs to be called after using miniflow_init().
Otherwise, if the miniflow mallocs data, then a memory leak may
occur.

Found by inspection.

Signed-off-by: Ryan Wilson <wryan@nicira.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>

lib/dpif-netdev.c

@@ -1363,6 +1363,7 @@ dpif_netdev_flow_put(struct dpif *dpif, const struct dpif_flow_put *put)
         }
     }
     ovs_mutex_unlock(&dp->flow_mutex);
+    miniflow_destroy(&miniflow);
 
     return error;
 }