The O2Micro controller only supports tuning at 4-bits. So the host driver
needs to change the bus width while tuning and then set it back when done.

There was a bug in the original implementation in that mmc->ios.bus_width
also wasn't updated. Thus setting the incorrect blocksize in
sdhci_send_tuning which results in a tuning failure.
Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Fixes: 0086fc21 ("mmc: sdhci: Add support for O2 hardware tuning")
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>