dpaa2-eth: retry the probe when the MAC is not yet discovered on the bus

The fsl_mc_get_endpoint() function now returns -EPROBE_DEFER when the
dpmac device was not yet discovered by the fsl-mc bus. When this
happens, pass the error code up so that we can retry the probe at a
later time.
Signed-off-by: NIoana Ciornei <ioana.ciornei@nxp.com>
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c

@@ -4042,7 +4042,11 @@ static int dpaa2_eth_connect_mac(struct dpaa2_eth_priv *priv)
 
 	dpni_dev = to_fsl_mc_device(priv->net_dev->dev.parent);
 	dpmac_dev = fsl_mc_get_endpoint(dpni_dev);
-	if (IS_ERR_OR_NULL(dpmac_dev) || dpmac_dev->dev.type != &fsl_mc_bus_dpmac_type)
+
+	if (PTR_ERR(dpmac_dev) == -EPROBE_DEFER)
+		return PTR_ERR(dpmac_dev);
+
+	if (IS_ERR(dpmac_dev) || dpmac_dev->dev.type != &fsl_mc_bus_dpmac_type)
 		return 0;
 
 	mac = kzalloc(sizeof(struct dpaa2_mac), GFP_KERNEL);