[dbus] close unsecure port when timeout is zero (#402)
[dbus] close unsecure port when timeout is zero (#402)

This is the behavior of the current client code. Update implementation
to be compatible.
jwhui/borderrouter,openthread/ot-br-posix,openthread/borderrouter,openthread/ot-br-posix,openthread/borderrouter,bukepo/borderrouter,openthread/ot-br-posix,openthread/ot-br-posix,openthread/borderrouter,openthread/borderrouter,jwhui/borderrouter,openthread/borderrouter,bukepo/borderrouter,openthread/ot-br-posix,openthread/ot-br-posix,jwhui/borderrouter,bukepo/borderrouter,jwhui/borderrouter,bukepo/borderrouter,jwhui/borderrouter,bukepo/borderrouter,openthread/borderrouter