mwifiex: correct TX byte count statistics

The skb is modified in sending the TX packet. Save the original
packet length to a variable so that we can get the correct
statistics update.

Signed-off-by: Ujjal Roy <royujjal@gmail.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/mwifiex/main.c

@@ -648,6 +648,7 @@ mwifiex_hard_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	tx_info = MWIFIEX_SKB_TXCB(skb);
 	tx_info->bss_num = priv->bss_num;
 	tx_info->bss_type = priv->bss_type;
+	tx_info->pkt_len = skb->len;
 
 	/* Record the current time the packet was queued; used to
 	 * determine the amount of time the packet was queued in