net: ti: icssg_prueth: Fix NULL pointer dereference in prueth_probe()

In the prueth_probe() function, if one of the calls to emac_phy_connect()
fails due to of_phy_connect() returning NULL, then the subsequent call to
phy_attached_info() will dereference a NULL pointer.

Check the return code of emac_phy_connect and fail cleanly if there is an
error.

Fixes: 128d587 ("net: ti: icssg-prueth: Add ICSSG ethernet driver")
Cc: stable@vger.kernel.org
Signed-off-by: Romain Gantois <romain.gantois@bootlin.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: MD Danish Anwar <danishanwar@ti.com>
Link: https://lore.kernel.org/r/20240521-icssg-prueth-fix-v1-1-b4b17b1433e9@bootlin.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Author: rgantois

drivers/net/ethernet/ti/icssg/icssg_prueth.c

@@ -1039,7 +1039,12 @@ static int prueth_probe(struct platform_device *pdev)
 
 		prueth->registered_netdevs[PRUETH_MAC0] = prueth->emac[PRUETH_MAC0]->ndev;
 
-		emac_phy_connect(prueth->emac[PRUETH_MAC0]);
+		ret = emac_phy_connect(prueth->emac[PRUETH_MAC0]);
+		if (ret) {
+			dev_err(dev,
+				"can't connect to MII0 PHY, error -%d", ret);
+			goto netdev_unregister;
+		}
 		phy_attached_info(prueth->emac[PRUETH_MAC0]->ndev->phydev);
 	}
 
@@ -1051,7 +1056,12 @@ static int prueth_probe(struct platform_device *pdev)
 		}
 
 		prueth->registered_netdevs[PRUETH_MAC1] = prueth->emac[PRUETH_MAC1]->ndev;
-		emac_phy_connect(prueth->emac[PRUETH_MAC1]);
+		ret = emac_phy_connect(prueth->emac[PRUETH_MAC1]);
+		if (ret) {
+			dev_err(dev,
+				"can't connect to MII1 PHY, error %d", ret);
+			goto netdev_unregister;
+		}
 		phy_attached_info(prueth->emac[PRUETH_MAC1]->ndev->phydev);
 	}