qcacld-3.0: unregister peer hang notifier

Currently, we register the peer hang notifier when the peer unmap
timer elapses, but do not unregister it. We also pass the peer reference
for which the unmap timeout happened as part of the notifier registry.

Since we do not unregister the notfier, there are chances that we
call the notifier with a stale peer reference during the subsequent
hang event which results in a crash; avoid this by unregistering the
peer hang notifier as part of device recovery.

Change-Id: I36bd8d9c1b4e38e1ba9d8c16b79df7f0cd1c9f82
CRs-Fixed: 2688676