net: devlink: Remove overzealous WARN_ON with snapshots

It is possible to trigger this WARN_ON from user space by triggering a
devlink snapshot with an ID which already exists. We don't need both
-EEXISTS being reported and spamming the kernel log.
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Tested-by: Chris Healy <cphealy@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/devlink.c

@@ -4063,7 +4063,7 @@ static int __devlink_snapshot_id_insert(struct devlink *devlink, u32 id)
 {
 	lockdep_assert_held(&devlink->lock);
 
-	if (WARN_ON(xa_load(&devlink->snapshot_ids, id)))
+	if (xa_load(&devlink->snapshot_ids, id))
 		return -EEXIST;
 
 	return xa_err(xa_store(&devlink->snapshot_ids, id, xa_mk_value(0),