arm/dt: msm8910: Add voltage regulator entries for SDC1 and SDC2

Enable SDC1 and SDC2 to control power to card slot and signal lines.
This is also needed for UHS-I initialization of SD3.0 cards.

Change-Id: Ifd7cea70e80d74257fb26a38db9b8a3847171b82
Signed-off-by: Oluwafemi Adeyemi <aadeyemi@codeaurora.org>