omap_hsmmc: do not re-power when powering off MMC

Remove code that turns MMC1 power back on after it
has been powered off (when the voltage is 1.8V).

The offending code is not necessary because the
host controller bus voltage is initialized to
3V when probing or resuming.  Note that MMC powers up
with the highest voltage available (see mmc_power_up())
which will be 3V also.

Signed-off-by: Adrian Hunter <ext-adrian.hunter@nokia.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>