wcn36xx: drain pending indicator messages on shutdown

When the interface is shut down, wcn36xx_smd_close() potentially races
against the queue worker. Make sure to cancel the work, and then free all
the remnants in hal_ind_queue manually.

This is again just a theoretical issue, not something that was triggered in
the wild.
Signed-off-by: Daniel Mack <daniel@zonque.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/ath/wcn36xx/smd.c

@@ -2513,5 +2513,11 @@ int wcn36xx_smd_open(struct wcn36xx *wcn)
 
 void wcn36xx_smd_close(struct wcn36xx *wcn)
 {
+	struct wcn36xx_hal_ind_msg *msg, *tmp;
+
+	cancel_work_sync(&wcn->hal_ind_work);
 	destroy_workqueue(wcn->hal_ind_wq);
+
+	list_for_each_entry_safe(msg, tmp, &wcn->hal_ind_queue, list)
+		kfree(msg);
 }