Revert "r8169: remove not needed call to dma_sync_single_for_device"

This reverts commit f072218c.

As reported by Aaro this patch causes network problems on
MIPS Loongson platform. Therefore revert it.

Fixes: f072218c ("r8169: remove not needed call to dma_sync_single_for_device")
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reported-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/realtek/r8169_main.c

@@ -5921,6 +5921,7 @@ static struct sk_buff *rtl8169_try_rx_copy(void *data,
 	skb = napi_alloc_skb(&tp->napi, pkt_size);
 	if (skb)
 		skb_copy_to_linear_data(skb, data, pkt_size);
+	dma_sync_single_for_device(d, addr, pkt_size, DMA_FROM_DEVICE);
 
 	return skb;
 }