net: num_dma_maps is not used

Get rid of num_dma_maps in struct skb_shared_info, as it seems unused.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/skbuff.h

@@ -194,9 +194,6 @@ struct skb_shared_info {
 	unsigned short  gso_type;
 	__be32          ip6_frag_id;
 	union skb_shared_tx tx_flags;
-#ifdef CONFIG_HAS_DMA
-	unsigned int	num_dma_maps;
-#endif
 	struct sk_buff	*frag_list;
 	struct skb_shared_hwtstamps hwtstamps;
 	skb_frag_t	frags[MAX_SKB_FRAGS];

net/core/skb_dma_map.c

@@ -30,7 +30,6 @@ int skb_dma_map(struct device *dev, struct sk_buff *skb,
 			goto unwind;
 		sp->dma_maps[i + 1] = map;
 	}
-	sp->num_dma_maps = i + 1;
 
 	return 0;