net: enetc: unregister mdiobus

If the device fails to probe - for example, when there is no
ethaddr set - then the private data is automatically freed
but the mdiobus remains registered.

Fixes: 1e354cb39314 ("drivers: net: fsl_enetc: register internal MDIO bus")
Signed-off-by: Michael Walle <michael@walle.cc>
diff --git a/drivers/net/fsl_enetc.c b/drivers/net/fsl_enetc.c
index 9b97a03..cd4c2c2 100644
--- a/drivers/net/fsl_enetc.c
+++ b/drivers/net/fsl_enetc.c
@@ -361,6 +361,9 @@
 {
 	struct enetc_priv *priv = dev_get_priv(dev);
 
+	if (miiphy_get_dev_by_name(priv->imdio.name))
+		mdio_unregister(&priv->imdio);
+
 	free(priv->enetc_txbd);
 	free(priv->enetc_rxbd);