staging: csr: fix the reset of skb mac header

mac_header can be offset if NET_SKBUFF_DATA_USES_OFFSET is set, so
we should call skb_reset_mac_header to reset mac_header.

Signed-off-by: Li RongQing <roy.qing.li@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/csr/monitor.c

@@ -188,7 +188,7 @@ netrx_radiotap(unifi_priv_t *priv,
 
 
     skb->dev = dev;
-    skb->mac_header = skb->data;
+    skb_reset_mac_header(skb);
     skb->pkt_type = PACKET_OTHERHOST;
     skb->protocol = __constant_htons(ETH_P_80211_RAW);
     memset(skb->cb, 0, sizeof(skb->cb));