mmc: core: add driver strength selection when selecting hs400es

The driver strength selection is missed and required when selecting
hs400es. So, It is added here.

Fixes: 81ac2af6

 ("mmc: core: implement enhanced strobe support")
Cc: stable@vger.kernel.org
Signed-off-by: Hankyung Yu <hankyung.yu@lge.com>
Signed-off-by: Chanho Min <chanho.min@lge.com>
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>