mmc: sdhci-msm: add registration to pm core framework

Add registration and initialization of platform driver to pm core for
system suspend/resume and runtime suspend/resume.
Platform device runtime power management uses the autosuspend pm core
feature with MSM_AUTOSUSPEND_DELAY (100ms).
MMC core power management is configured to aggressively suspend the card on
runtime suspend (and full initialization on runtime resume).

Change-Id: I45f0b2f1709361f41f7c38c57b95f692f8a0e486
Signed-off-by: Konstantin Dorfman <kdorfman@codeaurora.org>