ARM: ux500: Configure regulator for I/O voltage for SD-card slot

To be able to enable SDR12|25 for SD-cards, we needed to fixup the
configuration in DT of the gpio regulator, which handles the signal
voltage level. Some configuration were missing and some were wrong.

Cc: Lee Jones <lee.jones@linaro.org>
Cc: devicetree@vger.kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>