net: ll_temac: Fix iommu/swiotlb leak

Unmap the actual buffer length, not the amount of data received, avoiding
resource exhaustion of swiotlb (seen on x86_64 platform).
Signed-off-by: Esben Haabendal <esben@geanix.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/xilinx/ll_temac_main.c

@@ -820,7 +820,7 @@ static void ll_temac_recv(struct net_device *ndev)
 		length = be32_to_cpu(cur_p->app4) & 0x3FFF;
 
 		dma_unmap_single(ndev->dev.parent, be32_to_cpu(cur_p->phys),
-				 length, DMA_FROM_DEVICE);
+				 XTE_MAX_JUMBO_FRAME_SIZE, DMA_FROM_DEVICE);
 
 		skb_put(skb, length);
 		skb->protocol = eth_type_trans(skb, ndev);