forcedeth: correct valid flag

Elsewhere in the "optimized" functions, the "2" constants are used.
NV_TX_VALID and NV_TX2_VALID have the same value.
Signed-off-by: NJulia Lawall <julia@diku.dk>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/forcedeth.c

@@ -2468,7 +2468,7 @@ static int nv_tx_done_optimized(struct net_device *dev, int limit)
 	struct ring_desc_ex* orig_get_tx = np->get_tx.ex;
 
 	while ((np->get_tx.ex != np->put_tx.ex) &&
-	       !((flags = le32_to_cpu(np->get_tx.ex->flaglen)) & NV_TX_VALID) &&
+	       !((flags = le32_to_cpu(np->get_tx.ex->flaglen)) & NV_TX2_VALID) &&
 	       (tx_work < limit)) {
 
 		dprintk(KERN_DEBUG "%s: nv_tx_done_optimized: flags 0x%x.\n",