phy: fix xa_alloc_cyclic() error handling

xa_alloc_cyclic() can return 1, which isn't an error. To prevent
situation when the caller of this function will treat it as no error do
a check only for negative here.

Fixes: 3849687 ("net: phy: Introduce ethernet link topology representation")
Signed-off-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: Michal Swiatkowski

drivers/net/phy/phy_link_topology.c

@@ -73,7 +73,7 @@ int phy_link_topo_add_phy(struct net_device *dev,
 				      xa_limit_32b, &topo->next_phy_index,
 				      GFP_KERNEL);
 
-	if (ret)
+	if (ret < 0)
 		goto err;
 
 	return 0;