[media] af9033: cancel_delayed_work_sync before device removal / kfree

af9033_remove  was  calling  kfree(dev)  with  possibly  still  active
schedule_delayed_work(&dev->stat_work).   A  similar   bug  in  si2157
caused kernel panics in call_timer_fn e.g. after rmmod cx23885.

Signed-off-by: Ernst Martin Witte <emw-linux-kernel@nocabal.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/dvb-frontends/af9033.c

@@ -1372,6 +1372,9 @@ static int af9033_remove(struct i2c_client *client)
 
 	dev_dbg(&dev->client->dev, "\n");
 
+	/* stop statistics polling */
+	cancel_delayed_work_sync(&dev->stat_work);
+
 	dev->fe.ops.release = NULL;
 	dev->fe.demodulator_priv = NULL;
 	kfree(dev);