To support shutdown WLAN when system goes into suspend, add idle shutdown
when got PM_SUSPEND_PREPARE/PM_HIBERNATION_PREPARE.
Before suspend/shutdown, user space should stop adapter. And after resume,
user space should restart adapter. This can ensure user and kernel space
to sync adapter's state.
Change-Id: Id1f5172a7fc1792c83c8c1c20127de815f7e4980
CRs-Fixed: 3208931