net: tc35815: move free after the dereference

We dereference "skb" to get "skb->len" so we should probably do that
step before freeing the skb.

Fixes: eea221ce48 ("tc35815 driver update (take 2)")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/toshiba/tc35815.c

@@ -1017,8 +1017,8 @@ tc35815_free_queues(struct net_device *dev)
 			BUG_ON(lp->tx_skbs[i].skb != skb);
 #endif
 			if (skb) {
-				dev_kfree_skb(skb);
 				pci_unmap_single(lp->pci_dev, lp->tx_skbs[i].skb_dma, skb->len, PCI_DMA_TODEVICE);
+				dev_kfree_skb(skb);
 				lp->tx_skbs[i].skb = NULL;
 				lp->tx_skbs[i].skb_dma = 0;
 			}