mmc: host: sdhci: Add request_done ops for struct sdhci_ops

Add request_done ops for struct sdhci_ops as a preparation in case some
host controllers have different method to complete one request, such as
supporting request completion of MMC software queue.

Suggested-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Baolin Wang <baolin.wang7@gmail.com>
Link: https://lore.kernel.org/r/1539c801c8bbdbcd1d86f8c2dab375f5803c765a.1581478568.git.baolin.wang7@gmail.com


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>