mmc: sdhci: Do not allow tuning procedure to be interrupted

wait_event_interruptible_timeout() will return early if the blocked
process receives a signal, causing the driver to abort the tuning
procedure and possibly leaving the controller in a bad state.  Since the
tuning command is expected to complete quickly (<50ms) and we've set a
timeout, use wait_event_timeout() instead.

Signed-off-by: Christopher Freeman <cfreeman@nvidia.com>
Tested-by: Robert Foss <robert.foss@collabora.com>
Signed-off-by: Robert Foss <robert.foss@collabora.com>
Reviewed-by: Benson Leung <bleung@chromium.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>