To support shutdown WLAN when system goes into suspend, add idle shutdown
in cfg80211 suspend function.
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 state.
Idle shutdown must be processed in system active, so schedule delayed
work to execute it. After calling schedule, retrun EAGAIN directly to PM.
Change-Id: I08818517d05e7866d50e3f92cfdc9fa1a4d0e63f
CRs-Fixed: 3081480
675b9de61a