qemu: qapi: Return correct entry in virQEMUQAPISchemaTraverse
virQEMUQAPISchemaTraverse would return previous-to-last queried item on
a query. It would not be a problem if checking if the given path exists
since error reporting works properly but if the caller is interested in
the result, it would be wrong.
Signed-off-by: Peter Krempa <pkrempa@redhat.com>