networking: use skb_put_zero()

Use the recently introduced helper to replace the pattern of
skb_put() && memset(), this transformation was done with the
following spatch:

@@
identifier p;
expression len;
expression skb;
@@
-p = skb_put(skb, len);
-memset(p, 0, len);
+p = skb_put_zero(skb, len);

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bcm63xx_enet.c

@@ -609,8 +609,7 @@ static int bcm_enet_start_xmit(struct sk_buff *skb, struct net_device *dev)
 			dev_kfree_skb(skb);
 			skb = nskb;
 		}
-		data = skb_put(skb, needed);
-		memset(data, 0, needed);
+		data = skb_put_zero(skb, needed);
 	}
 
 	/* point to the next available desc */