mmc: sdhci: Remove ->select_drive_strength() callback

Drivers can use the host operation directly, so remove this now unused
callback.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Ludovic Desroches <ludovic.desroches@microchip.com>
4 files changed