mac80211_hwsim: 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>

drivers/net/wireless/mac80211_hwsim.c

@@ -844,7 +844,7 @@ static void mac80211_hwsim_monitor_rx(struct ieee80211_hw *hw,
 	hdr->rt_chbitmask = cpu_to_le16(flags);
 
 	skb->dev = hwsim_mon;
-	skb_set_mac_header(skb, 0);
+	skb_reset_mac_header(skb);
 	skb->ip_summed = CHECKSUM_UNNECESSARY;
 	skb->pkt_type = PACKET_OTHERHOST;
 	skb->protocol = htons(ETH_P_802_2);
@@ -887,7 +887,7 @@ static void mac80211_hwsim_monitor_ack(struct ieee80211_channel *chan,
 	memcpy(hdr11->addr1, addr, ETH_ALEN);
 
 	skb->dev = hwsim_mon;
-	skb_set_mac_header(skb, 0);
+	skb_reset_mac_header(skb);
 	skb->ip_summed = CHECKSUM_UNNECESSARY;
 	skb->pkt_type = PACKET_OTHERHOST;
 	skb->protocol = htons(ETH_P_802_2);