net: dont use __netdev_alloc_skb for bounce buffer

commit a1c7fff7e1 (net: netdev_alloc_skb() use build_skb()) broke b44 on
some 64bit machines.

It appears b44 and b43 use __netdev_alloc_skb() instead of alloc_skb()
for their bounce buffers.

There is no need to add an extra NET_SKB_PAD reservation for bounce
buffers :

- In TX path, NET_SKB_PAD is useless

- In RX path in b44, we force a copy of incoming frames if
  GFP_DMA allocations were needed.

Reported-and-bisected-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/wireless/b43legacy/dma.c b/drivers/net/wireless/b43legacy/dma.c
index f1f8bd0..c8baf02 100644
--- a/drivers/net/wireless/b43legacy/dma.c
+++ b/drivers/net/wireless/b43legacy/dma.c
@@ -1072,7 +1072,7 @@
 	meta->dmaaddr = map_descbuffer(ring, skb->data, skb->len, 1);
 	/* create a bounce buffer in zone_dma on mapping failure. */
 	if (b43legacy_dma_mapping_error(ring, meta->dmaaddr, skb->len, 1)) {
-		bounce_skb = __dev_alloc_skb(skb->len, GFP_ATOMIC | GFP_DMA);
+		bounce_skb = alloc_skb(skb->len, GFP_ATOMIC | GFP_DMA);
 		if (!bounce_skb) {
 			ring->current_slot = old_top_slot;
 			ring->used_slots = old_used_slots;