rtlwifi: usb: add missing freeing of skbuff

commit 36ef0b47 upstream.
Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>
Acked-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/net/wireless/rtlwifi/usb.c

@@ -812,6 +812,7 @@ static void _rtl_usb_transmit(struct ieee80211_hw *hw, struct sk_buff *skb,
 	if (unlikely(!_urb)) {
 		RT_TRACE(rtlpriv, COMP_ERR, DBG_EMERG,
 			 ("Can't allocate urb. Drop skb!\n"));
+		kfree_skb(skb);
 		return;
 	}
 	urb_list = &rtlusb->tx_pending[ep_num];