sky2: fix transmit DMA map leakage

The book keeping structure for transmit always had the flags value
cleared so transmit DMA maps were never released correctly.
Based on patch by Jarek Poplawski, problem observed by Michael Breuer.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/sky2.c b/drivers/net/sky2.c
index d760650..67249c3 100644
--- a/drivers/net/sky2.c
+++ b/drivers/net/sky2.c
@@ -1025,11 +1025,8 @@
 static inline struct sky2_tx_le *get_tx_le(struct sky2_port *sky2, u16 *slot)
 {
 	struct sky2_tx_le *le = sky2->tx_le + *slot;
-	struct tx_ring_info *re = sky2->tx_ring + *slot;
 
 	*slot = RING_NEXT(*slot, sky2->tx_ring_size);
-	re->flags = 0;
-	re->skb = NULL;
 	le->ctrl = 0;
 	return le;
 }
@@ -1622,8 +1619,7 @@
 	return count;
 }
 
-static void sky2_tx_unmap(struct pci_dev *pdev,
-			  const struct tx_ring_info *re)
+static void sky2_tx_unmap(struct pci_dev *pdev, struct tx_ring_info *re)
 {
 	if (re->flags & TX_MAP_SINGLE)
 		pci_unmap_single(pdev, pci_unmap_addr(re, mapaddr),
@@ -1633,6 +1629,7 @@
 		pci_unmap_page(pdev, pci_unmap_addr(re, mapaddr),
 			       pci_unmap_len(re, maplen),
 			       PCI_DMA_TODEVICE);
+	re->flags = 0;
 }
 
 /*
@@ -1839,6 +1836,7 @@
 			dev->stats.tx_packets++;
 			dev->stats.tx_bytes += skb->len;
 
+			re->skb = NULL;
 			dev_kfree_skb_any(skb);
 
 			sky2->tx_next = RING_NEXT(idx, sky2->tx_ring_size);