amd-xgbe: Add check to be sure amd-xgbe-phy driver is used

The amd-xgbe driver relies on the amd-xgbe-phy phylib driver. Add a
check to be sure that if any errors occur during probing of the
amd-xgbe-phy driver then the amd-xgbe driver returns an error.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/amd/xgbe/xgbe-mdio.c

@@ -260,10 +260,14 @@ int xgbe_mdio_register(struct xgbe_prv_data *pdata)
 		of_node_put(phy_node);
 		goto err_phy_device;
 	}
+	if (!phydev->dev.driver) {
+		dev_err(pdata->dev, "phy driver probe failed\n");
+		ret = -EIO;
+		goto err_phy_device;
+	}
 
 	/* Add a reference to the PHY driver so it can't be unloaded */
-	pdata->phy_module = phydev->dev.driver ?
-			    phydev->dev.driver->owner : NULL;
+	pdata->phy_module = phydev->dev.driver->owner;
 	if (!try_module_get(pdata->phy_module)) {
 		dev_err(pdata->dev, "try_module_get failed\n");
 		ret = -EIO;