net: phy: Fix return value check in xgmiitorgmii_probe()

In case of error, the function of_parse_phandle() returns NULL
pointer not ERR_PTR(). The IS_ERR() test in the return value check
should be replaced with NULL test.
Signed-off-by: NWei Yongjun <weiyj.lk@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/phy/xilinx_gmii2rgmii.c

@@ -67,7 +67,7 @@ int xgmiitorgmii_probe(struct mdio_device *mdiodev)
 		return -ENOMEM;
 
 	phy_node = of_parse_phandle(np, "phy-handle", 0);
-	if (IS_ERR(phy_node)) {
+	if (!phy_node) {
 		dev_err(dev, "Couldn't parse phy-handle\n");
 		return -ENODEV;
 	}