forcedeth: replace pci_unmap_page with dma_unmap_page

The function pci_unmap_page is obsolete. So it is replaced with
the function dma_unmap_page.

CC: Srinivas Eeda <srinivas.eeda@oracle.com>
CC: Joe Jin <joe.jin@oracle.com>
CC: Junxiao Bi <junxiao.bi@oracle.com>
Signed-off-by: NZhu Yanjun <yanjun.zhu@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/nvidia/forcedeth.c

@@ -1986,9 +1986,9 @@ static void nv_unmap_txskb(struct fe_priv *np, struct nv_skb_map *tx_skb)
 					 tx_skb->dma_len,
 					 DMA_TO_DEVICE);
 		else
-			pci_unmap_page(np->pci_dev, tx_skb->dma,
+			dma_unmap_page(&np->pci_dev->dev, tx_skb->dma,
 				       tx_skb->dma_len,
-				       PCI_DMA_TODEVICE);
+				       DMA_TO_DEVICE);
 		tx_skb->dma = 0;
 	}
 }