drivers: net: cpsw: fix phy dt node setting

Now CPSW 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>
diff --git a/drivers/net/cpsw.c b/drivers/net/cpsw.c
index 9919d39..c31695e 100644
--- a/drivers/net/cpsw.c
+++ b/drivers/net/cpsw.c
@@ -999,7 +999,7 @@
 
 #ifdef CONFIG_DM_ETH
 	if (slave->data->phy_of_handle)
-		dev_set_of_offset(phydev->dev, slave->data->phy_of_handle);
+		phydev->node = offset_to_ofnode(slave->data->phy_of_handle);
 #endif
 
 	priv->phydev = phydev;