bnx2x: use reset to set network header

Since offset is zero, it's not necessary to use set function. Reset
function is straightforward, and will remove the unnecessary add
operation in set function.
Signed-off-by: NZhang Shengju <zhangshengju@cmss.chinamobile.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c

@@ -724,7 +724,7 @@ static void bnx2x_gro_ipv6_csum(struct bnx2x *bp, struct sk_buff *skb)
 static void bnx2x_gro_csum(struct bnx2x *bp, struct sk_buff *skb,
 			    void (*gro_func)(struct bnx2x*, struct sk_buff*))
 {
-	skb_set_network_header(skb, 0);
+	skb_reset_network_header(skb);
 	gro_func(bp, skb);
 	tcp_gro_complete(skb);
 }