staging: r8712u: Do not queue cloned skb

Some post-3.4 kernels have a problem when a cloned skb is used in the
RX path. This patch handles one such case for r8712u.

The patch was suggested by Eric Dumazet.
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Stable <stable@vger.kernel.org>  [v3.4+]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8712/rtl8712_recv.c

@@ -1131,6 +1131,9 @@ static void recv_tasklet(void *priv)
 		recvbuf2recvframe(padapter, pskb);
 		skb_reset_tail_pointer(pskb);
 		pskb->len = 0;
-		skb_queue_tail(&precvpriv->free_recv_skb_queue, pskb);
+		if (!skb_cloned(pskb))
+			skb_queue_tail(&precvpriv->free_recv_skb_queue, pskb);
+		else
+			consume_skb(pskb);
 	}
 }