The driver decide whether use MOSI/MISO phases according to the buffer
address together with the SPI_TRANS_USE_*DATA. However someone may assue
that these phases will be skipped when the ``length``/``rxlength`` is
set to 0. In fact it is a feature that ``rxlength`` is allowed to be
set to 0 when tx and rx have the same length, and the driver fill the
``rxlength`` to ``length``.
An error check is added when the rxlength is 0 but there is data to be
sent.