mmc: tegra: Reconfigure pad voltages during voltage switching

Parse the pinctrl state and nvidia,only-1-8-v properties from the device
tree. Validate the pinctrl and regulator configuration before unmasking
UHS modes. Implement pad voltage state reconfiguration in the mmc
start_signal_voltage_switch() callback. Add NVQUIRK_NEEDS_PAD_CONTROL
and add set it for Tegra210 and Tegra186.

The pad configuration is done in the mmc callback because the order of
pad reconfiguration and sdhci voltage switch depend on the voltage to
which the transition occurs.

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>