mmc: sdhci: Clear also HS400 1.2V capability if 1.2V is not supported

1.2V HS200 mode capability is cleared if there is not a voltage
regulator that supports 1.2V.  Do the same for 1.2V HS400 mode.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>