spi: sh-msiof: Improve transfer error handling

  - Add a timeout when waiting for the transfer complete interrupt,
  - If sh_msiof_spi_stop() fails, there's no need to clear IER, as the
    interrupt handler has already done that,
  - Propagate transfer failures in sh_msiof_transfer_one().

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@linaro.org>