net: tsi108: use NULL for pointer-typed argument

The first argument of pci_free_consistent has type struct pci_dev *, so use
NULL instead of 0.

The semantic patch that performs this transformation is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@@
@@
pci_free_consistent(
- 0
+ NULL
  , ...)
// </smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/tundra/tsi108_eth.c

@@ -1314,7 +1314,8 @@ static int tsi108_open(struct net_device *dev)
 	data->txring = dma_zalloc_coherent(NULL, txring_size, &data->txdma,
 					   GFP_KERNEL);
 	if (!data->txring) {
-		pci_free_consistent(0, rxring_size, data->rxring, data->rxdma);
+		pci_free_consistent(NULL, rxring_size, data->rxring,
+				    data->rxdma);
 		return -ENOMEM;
 	}