DMA-API: net: octeon: use dma_coerce_mask_and_coherent()

The code sequence:
	pdev->dev.coherent_dma_mask = DMA_BIT_MASK(64);
	pdev->dev.dma_mask = &pdev->dev.coherent_dma_mask;
bypasses the architectures check on the DMA mask.  It can be replaced
with dma_coerce_mask_and_coherent(), avoiding the direct initialization
of this mask.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

drivers/net/ethernet/octeon/octeon_mgmt.c

@@ -1552,8 +1552,9 @@ static int octeon_mgmt_probe(struct platform_device *pdev)
 
 	p->phy_np = of_parse_phandle(pdev->dev.of_node, "phy-handle", 0);
 
-	pdev->dev.coherent_dma_mask = DMA_BIT_MASK(64);
-	pdev->dev.dma_mask = &pdev->dev.coherent_dma_mask;
+	result = dma_coerce_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
+	if (result)
+		goto err;
 
 	netif_carrier_off(netdev);
 	result = register_netdev(netdev);