Ath5k: kill tasklets on shutdown

Don't forget to kill tasklets on stop to not panic if they
fire after freeing some structures.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Acked-by: Nick Kossifidis <mickflemm@gmail.com>
Cc: Luis R. Rodriguez <mcgrof@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath5k/base.c b/drivers/net/wireless/ath5k/base.c
index ed51c4a..c5bf8a2 100644
--- a/drivers/net/wireless/ath5k/base.c
+++ b/drivers/net/wireless/ath5k/base.c
@@ -2342,6 +2342,9 @@
 	mutex_unlock(&sc->lock);
 
 	del_timer_sync(&sc->calib_tim);
+	tasklet_kill(&sc->rxtq);
+	tasklet_kill(&sc->txtq);
+	tasklet_kill(&sc->restq);
 
 	return ret;
 }