libfdt: overlay: Report a bad overlay for mismatching local fixups

The __local_fixups__ node as a structure that mimics the structure of the
main overlay part.

This means that if we have a child node somewhere in the local fixups
sub-tree and if that node is not present in the main tree, the overlay is
poorly formatted, and we should report it as such.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

libfdt/fdt_overlay.c

@@ -272,6 +272,8 @@ static int overlay_update_local_node_references(void *fdto,
 
 		tree_child = fdt_subnode_offset(fdto, tree_node,
 						fixup_child_name);
+		if (ret == -FDT_ERR_NOTFOUND)
+			return -FDT_ERR_BADOVERLAY;
 		if (tree_child < 0)
 			return tree_child;