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: 384968786909 ("net: phy: Introduce ethernet link topology representation")
Signed-off-by: Michal Swiatkowski <[e-mail]>
Reviewed-by: Maxime Chevallier <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/phy/phy_link_topology.c

···
 				      xa_limit_32b, &topo->next_phy_index,
 				      GFP_KERNEL);
 
-	if (ret)
+	if (ret < 0)
 		goto err;
 
 	return 0;