mmc: tmio: enforce retune after runtime suspend

Currently, select_tuning() is called after RPM resume. But
select_tuning() needs some additional function calls to work correctly.
Instead of reimplementing the whole postprocessing, just enforce
retuning.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Link: https://lore.kernel.org/r/20200129203709.30493-5-wsa+renesas@sang-engineering.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>