net: phy: propagate an error back to the callers of phy_sfp_probe

The compilation warning below reveals that the errors returned from
the sfp_bus_add_upstream() call are not propagated to the callers.
Fix it by returning "ret".

14:37:51 drivers/net/phy/phy_device.c: In function 'phy_sfp_probe':
14:37:51 drivers/net/phy/phy_device.c:1236:6: warning: variable 'ret'
   set but not used [-Wunused-but-set-variable]
14:37:51  1236 |  int ret;
14:37:51       |      ^~~

Fixes: 298e54fa ("net: phy: add core phylib sfp support")
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/phy_device.c

@@ -1233,7 +1233,7 @@ int phy_sfp_probe(struct phy_device *phydev,
 		  const struct sfp_upstream_ops *ops)
 {
 	struct sfp_bus *bus;
-	int ret;
+	int ret = 0;
 
 	if (phydev->mdio.dev.fwnode) {
 		bus = sfp_bus_find_fwnode(phydev->mdio.dev.fwnode);
@@ -1245,7 +1245,7 @@ int phy_sfp_probe(struct phy_device *phydev,
 		ret = sfp_bus_add_upstream(bus, phydev, ops);
 		sfp_bus_put(bus);
 	}
-	return 0;
+	return ret;
 }
 EXPORT_SYMBOL(phy_sfp_probe);