s390/qeth: move netif_napi_add_tx() and napi_enable() from under BH

Like other drivers qeth is calling local_bh_enable() after napi_schedule()
to kick-start softirqs [0].
Since netif_napi_add_tx() and napi_enable() now take the netdev_lock()
mutex [1], move them out from under the BH protection. Same solution as in
commit a605586 ("wifi: mt76: move napi_enable() from under BH")

Fixes: 1b23cdb ("net: protect netdev->napi_list with netdev_lock()")
Link: https://lore.kernel.org/netdev/20240612181900.4d9d18d0@kernel.org/ [0]
Link: https://lore.kernel.org/netdev/20250115035319.559603-1-kuba@kernel.org/ [1]
Signed-off-by: Alexandra Winter <wintera@linux.ibm.com>
Acked-by: Joe Damato <jdamato@fastly.com>
Link: https://patch.msgid.link/20250212163659.2287292-1-wintera@linux.ibm.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: SandyWinter

drivers/s390/net/qeth_core_main.c

@@ -7050,14 +7050,16 @@ int qeth_open(struct net_device *dev)
 	card->data.state = CH_STATE_UP;
 	netif_tx_start_all_queues(dev);
 
-	local_bh_disable();
 	qeth_for_each_output_queue(card, queue, i) {
 		netif_napi_add_tx(dev, &queue->napi, qeth_tx_poll);
 		napi_enable(&queue->napi);
-		napi_schedule(&queue->napi);
 	}
-
 	napi_enable(&card->napi);
+
+	local_bh_disable();
+	qeth_for_each_output_queue(card, queue, i) {
+		napi_schedule(&queue->napi);
+	}
 	napi_schedule(&card->napi);
 	/* kick-start the NAPI softirq: */
 	local_bh_enable();