Improve the suspend and resume callbacks in DaVinci MMC host controller driver.
Modify the reset status of the contorller and clock during suspend and resume.
Also migrate the power management callbacks from platform driver to dev_pm_ops
structure.

Tested on DA850/OMAP-L138 EVM.
Signed-off-by: Chaithrika U S <chaithrika@ti.com>
Acked-by: Kevin Hilman <khilman@deeprootsystems.com>