wireless: use reset to set mac 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: Zhang Shengju <zhangshengju@cmss.chinamobile.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/wireless/util.c

@@ -636,7 +636,7 @@ int ieee80211_data_from_8023(struct sk_buff *skb, const u8 *addr,
 	/* Update skb pointers to various headers since this modified frame
 	 * is going to go through Linux networking code that may potentially
 	 * need things like pointer to IP header. */
-	skb_set_mac_header(skb, 0);
+	skb_reset_mac_header(skb);
 	skb_set_network_header(skb, nh_pos);
 	skb_set_transport_header(skb, h_pos);