qeth: delete napi struct when removing a qeth device

A qeth_card contains a napi_struct linked to the net_device during
device probing. This struct must be deleted when removing the qeth
device, otherwise Panic on oops can occur when qeth devices are
repeatedly removed and added.

Fixes: a1c3ed4c ("qeth: NAPI support for l2 and l3 discipline")
Cc: stable@vger.kernel.org # v2.6.37+
Signed-off-by: NUrsula Braun <ubraun@linux.vnet.ibm.com>
Tested-by: NAlexander Klein <ALKL@de.ibm.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/s390/net/qeth_l2_main.c

@@ -1051,6 +1051,7 @@ static void qeth_l2_remove_device(struct ccwgroup_device *cgdev)
 		qeth_l2_set_offline(cgdev);
 
 	if (card->dev) {
+		netif_napi_del(&card->napi);
 		unregister_netdev(card->dev);
 		card->dev = NULL;
 	}

drivers/s390/net/qeth_l3_main.c

@@ -3226,6 +3226,7 @@ static void qeth_l3_remove_device(struct ccwgroup_device *cgdev)
 		qeth_l3_set_offline(cgdev);
 
 	if (card->dev) {
+		netif_napi_del(&card->napi);
 		unregister_netdev(card->dev);
 		card->dev = NULL;
 	}