mmc: revert runtime idle state

Remove the runtime idle state. It was introduced by
217cf955
Instead of checking BKOPS logic in the runtime idle state, all relevant
logic should be performed in runtime suspend callback.

CRs-Fixed: 979630
Change-Id: Iaf0d8326c0e3fd6507b075339f2cc87ae1bdf6b2
Signed-off-by: Konstantin Dorfman <kdorfman@codeaurora.org>