drivers: net: zynq_gem: fix phy dt node setting

Now zynq_gem driver will overwrite UCLASS_ETH node when PHY is
connected and configured which is not correct.
Use struct phydev->node instead.

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
Tested-by: Siva Durga Prasad Paladugu <siva.durga.paladugu@xilinx.com>

drivers/net/zynq_gem.c

@@ -350,7 +350,7 @@ static int zynq_phy_init(struct udevice *dev)
 	priv->phydev->advertising = priv->phydev->supported;
 
 	if (priv->phy_of_handle > 0)
-		dev_set_of_offset(priv->phydev->dev, priv->phy_of_handle);
+		priv->phydev->node = offset_to_ofnode(priv->phy_of_handle);
 
 	return phy_config(priv->phydev);
 }