r8169: fix DMA issue on MIPS platform

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

Fixes: f072218cca ("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

@@ -5822,6 +5822,10 @@ process_pkt:
 			skb->tail += pkt_size;
 			skb->len = pkt_size;
 
+			dma_sync_single_for_device(tp_to_dev(tp),
+						   le64_to_cpu(desc->addr),
+						   pkt_size, DMA_FROM_DEVICE);
+
 			rtl8169_rx_csum(skb, status);
 			skb->protocol = eth_type_trans(skb, dev);