qcacld-3.0: Move from qdf event to linux completion for vdev destroy

Whenever there is a process waiting on a response from firmware it has the
option of using either a qdf_event or a linux completion event.
The primary difference between these is that if there is an SSR all
qdf_events are immediately completed whereas Linux completion events are
only completed by the normal flow of code.

With new upcoming changes SSR processing will take the normal path for
releasing all of its resources, and the qdf_session_close_event is used for
synchronization.
If we define this as a qdf_event, it will be completed when the SSR begins,
defeating its purpose.

Therefore change this to be a Linux completion event.

Change-Id: Ia6fe504e2a2d01f12c3d3446fffc2fc397566966
CRs-Fixed: 2586190
3 files changed