linux-phytec-fsl

mmc: mxs-mmc: enable regulator for mmc slot

If bootloader or platform initialization code does not enable the
power supply to mmc slot, we need to do it in mmc driver.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Chris Ball <cjb@laptop.org>