net: davinci: support of_get_mac_address new ERR_PTR error

There was NVMEM support added directly to of_get_mac_address, and it uses
nvmem_get_mac_address under the hood, so we can remove it. As
of_get_mac_address can now return ERR_PTR encoded error values, adjust to
that as well.
Signed-off-by: Petr Štetiar <ynezz@true.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/ti/davinci_emac.c

@@ -1700,7 +1700,7 @@ davinci_emac_of_get_pdata(struct platform_device *pdev, struct emac_priv *priv)
 
 	if (!is_valid_ether_addr(pdata->mac_addr)) {
 		mac_addr = of_get_mac_address(np);
-		if (mac_addr)
+		if (!IS_ERR(mac_addr))
 			ether_addr_copy(pdata->mac_addr, mac_addr);
 	}
 
@@ -1898,16 +1898,12 @@ static int davinci_emac_probe(struct platform_device *pdev)
 		ether_addr_copy(ndev->dev_addr, priv->mac_addr);
 
 	if (!is_valid_ether_addr(priv->mac_addr)) {
-		/* Try nvmem if MAC wasn't passed over pdata or DT. */
-		rc = nvmem_get_mac_address(&pdev->dev, priv->mac_addr);
-		if (rc) {
 		/* Use random MAC if still none obtained. */
 		eth_hw_addr_random(ndev);
 		memcpy(priv->mac_addr, ndev->dev_addr, ndev->addr_len);
 		dev_warn(&pdev->dev, "using random MAC addr: %pM\n",
 			 priv->mac_addr);
 	}
-	}
 
 	ndev->netdev_ops = &emac_netdev_ops;
 	ndev->ethtool_ops = &ethtool_ops;