qcacmn: Flush Rx diag event work during idle shutdown

Currently, Rx diag event work is not being flushed during idle shutdown.
This may result in use after free access if the scheduled diag event work
gets the chance to execute after driver modules are closed.

To address this, flush diag events work during idle shutdown.

Change-Id: I348e80d2c86a5e070f0fb67d66b758529fede76c
CRs-Fixed: 2838020

wmi/src/wmi_unified.c

@@ -3182,6 +3182,7 @@ void wmi_unified_detach(struct wmi_unified *wmi_handle)
 						&soc->wmi_pdev[i]->event_queue);
 			}
 
+			qdf_flush_work(&soc->wmi_pdev[i]->rx_diag_event_work);
 			buf = qdf_nbuf_queue_remove(
 					&soc->wmi_pdev[i]->diag_event_queue);
 			while (buf) {
@@ -3253,6 +3254,16 @@ wmi_unified_remove_work(struct wmi_unified *wmi_handle)
 		buf = qdf_nbuf_queue_remove(&wmi_handle->event_queue);
 	}
 	qdf_spin_unlock_bh(&wmi_handle->eventq_lock);
+
+	/* Remove diag events work */
+	qdf_flush_work(&wmi_handle->rx_diag_event_work);
+	qdf_spin_lock_bh(&wmi_handle->diag_eventq_lock);
+	buf = qdf_nbuf_queue_remove(&wmi_handle->diag_event_queue);
+	while (buf) {
+		qdf_nbuf_free(buf);
+		buf = qdf_nbuf_queue_remove(&wmi_handle->diag_event_queue);
+	}
+	qdf_spin_unlock_bh(&wmi_handle->diag_eventq_lock);
 }
 
 /**