net: ll_temac: Fix an NULL vs IS_ERR() check in temac_open()

The phy_connect() function doesn't return NULL pointers.  It returns
error pointers on error, so I have updated the check.

Fixes: 8425c41d ("net: ll_temac: Extend support to non-device-tree platforms")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/xilinx/ll_temac_main.c

@@ -927,9 +927,9 @@ static int temac_open(struct net_device *ndev)
 	} else if (strlen(lp->phy_name) > 0) {
 		phydev = phy_connect(lp->ndev, lp->phy_name, temac_adjust_link,
 				     lp->phy_interface);
-		if (!phydev) {
+		if (IS_ERR(phydev)) {
 			dev_err(lp->dev, "phy_connect() failed\n");
-			return -ENODEV;
+			return PTR_ERR(phydev);
 		}
 		phy_start(phydev);
 	}