phy: mvebu-cp110: checking for NULL instead of IS_ERR()

devm_ioremap_resource() never returns NULL, it only returns error
pointers so this test needs to be changed.

Fixes: d0438bd6 ("phy: add the mvebu cp110 comphy driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

drivers/phy/marvell/phy-mvebu-cp110-comphy.c

@@ -586,8 +586,8 @@ static int mvebu_comphy_probe(struct platform_device *pdev)
 		return PTR_ERR(priv->regmap);
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	priv->base = devm_ioremap_resource(&pdev->dev, res);
-	if (!priv->base)
-		return -ENOMEM;
+	if (IS_ERR(priv->base))
+		return PTR_ERR(priv->base);
 
 	for_each_available_child_of_node(pdev->dev.of_node, child) {
 		struct mvebu_comphy_lane *lane;