mmc: sdhci: Platform hooks for handling power off

Added platform specific callback to allow for any special handling of
MMC_POWER_OFF.
Bug 1353926

Change-Id: I0918984461746ff28824b7dd2873b652225e3d1a
Signed-off-by: Pavan Kunapuli <pkunapuli@nvidia.com>
Reviewed-on: http://git-master/r/267312
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Bitan Biswas <bbiswas@nvidia.com>
2 files changed