libertas: Fix a double free in if_spi_c2h_data()

The lbs_process_rxed_packet() frees the skb.  It didn't originally, but
we fixed it in commit f54930f3 ("libertas: don't leak skb on receive
error").
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NDan Williams <dcbw@redhat.com>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/marvell/libertas/if_spi.c

@@ -766,19 +766,15 @@ static int if_spi_c2h_data(struct if_spi_card *card)
 
 	/* Read the data from the WLAN module into our skb... */
 	err = spu_read(card, IF_SPI_DATA_RDWRPORT_REG, data, ALIGN(len, 4));
-	if (err)
-		goto free_skb;
+	if (err) {
+		dev_kfree_skb(skb);
+		goto out;
+	}
 
 	/* pass the SKB to libertas */
 	err = lbs_process_rxed_packet(card->priv, skb);
-	if (err)
-		goto free_skb;
-
-	/* success */
-	goto out;
+	/* lbs_process_rxed_packet() consumes the skb */
 
-free_skb:
-	dev_kfree_skb(skb);
 out:
 	if (err)
 		netdev_err(priv->dev, "%s: err=%d\n", __func__, err);