mmc: tegra: Perform pad calibration after voltage switch

Run the automatic pad calibration after voltage switching if
tegra_host->pad_calib_required is set.

Signed-off-by: Aapo Vienamo <avienamo@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>