mmc: msm_sdcc: Turn off clocks if there is no active request

Turn off SDCC clocks when there is no active request posted to
the driver. This saves power and allows TCXO shutdown
in idle power collapse. This is useful when CONFIG_PM_RUNTIME
is disabled, otherwise the same it is taken care by runtime PM
functionality. The disable delay is set to 200msecs as not to be
aggressive which can impact performance.

Change-Id: Iaa91a02ad9b146c0fea98ba2d4880dc80c4d1ace
Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>