mmc: During unsafe resume, select the right volatge for the card

During mmc unsafe resume, choose the right voltage for the card after
powerup.

Although this has not seen to cause trouble, it's the wrong behaviour.

Signed-off-by: Balaji Rao <balajirrao@openmoko.org>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>