mmc: Make sure host is disabled on suspend

Change-Id: Ie0bf2004e173cef8dad66722a152658d7727ab65
Signed-off-by: Dmitry Shmidt <dimitrysh@google.com>
OMAP4: hsmmc: fix race conditions in suspend/resume path

using mmc_host_enable/disable causes race conditions. By using
runtime pm framework during hsmmc suspend/resume, clock management
integrity is kept, thereby avoid race conditions