staging: fsl-dpaa2/eth: Fix DMA mapping direction

We are using DMA_FROM_DEVICE when mapping RX frame buffers,
but DMA_BIDIRECTIONAL for unmap. Fix the direction for DMA
unmapping operation.

Fixes: 87eb55e4 ("staging: fsl-dpaa2/eth: Fix potential endless loop")
Signed-off-by: Ioana Radulescu <ruxandra.radulescu@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/fsl-dpaa2/ethernet/dpaa2-eth.c

@@ -767,7 +767,7 @@ static void free_bufs(struct dpaa2_eth_priv *priv, u64 *buf_array, int count)
 	for (i = 0; i < count; i++) {
 		vaddr = dpaa2_iova_to_virt(priv->iommu_domain, buf_array[i]);
 		dma_unmap_single(dev, buf_array[i], DPAA2_ETH_RX_BUF_SIZE,
-				 DMA_BIDIRECTIONAL);
+				 DMA_FROM_DEVICE);
 		skb_free_frag(vaddr);
 	}
 }