s390/qeth: allocate skb from NAPI cache

napi_alloc_skb() doesn't need to disable IRQs during the allocation,
and thus may save us a few cycles.
Doing so requires a small fix-up in the HiperTransport path, which
currently assumes a fixed NET_SKB_PAD headroom padding. napi_alloc_skb()
adds an additional NET_IP_ALIGN padding, so use the proper helper for
setting up the mac_header offset.

Use this opportunity to convert the non-NAPI path to netdev_alloc_skb(),
which means that skb->dev is now always set-up during allocation and
doesn't need to be assigned manually.

Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c
index 8e8818e..283cbdc 100644
--- a/drivers/s390/net/qeth_l3_main.c
+++ b/drivers/s390/net/qeth_l3_main.c
@@ -1572,7 +1572,6 @@ static int qeth_l3_process_inbound_buffer(struct qeth_card *card,
 			*done = 1;
 			break;
 		}
-		skb->dev = card->dev;
 		switch (hdr->hdr.l3.id) {
 		case QETH_HEADER_TYPE_LAYER3:
 			magic = *(__u16 *)skb->data;
@@ -1580,11 +1579,10 @@ static int qeth_l3_process_inbound_buffer(struct qeth_card *card,
 			    (magic == ETH_P_AF_IUCV)) {
 				skb->protocol = cpu_to_be16(ETH_P_AF_IUCV);
 				skb->pkt_type = PACKET_HOST;
-				skb->mac_header = NET_SKB_PAD;
-				skb->dev = card->dev;
 				len = skb->len;
 				card->dev->header_ops->create(skb, card->dev, 0,
 					card->dev->dev_addr, "FAKELL", len);
+				skb_reset_mac_header(skb);
 				netif_receive_skb(skb);
 			} else {
 				qeth_l3_rebuild_skb(card, skb, hdr);