net: ethernet: mvneta: Fix error handling in mvneta_probe

When mvneta_port_power_up() fails, we should execute
cleanup functions after label err_netdev to avoid memleak.

Fixes: 41c2b6b4 ("net: ethernet: mvneta: Add back interface mode validation")
Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
Link: https://lore.kernel.org/r/20201220082930.21623-1-dinghao.liu@zju.edu.cnSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/marvell/mvneta.c

@@ -5255,7 +5255,7 @@ static int mvneta_probe(struct platform_device *pdev)
 	err = mvneta_port_power_up(pp, pp->phy_interface);
 	if (err < 0) {
 		dev_err(&pdev->dev, "can't power up port\n");
-		return err;
+		goto err_netdev;
 	}
 
 	/* Armada3700 network controller does not support per-cpu