Relax subgraph byte constraint to `required_bytes <= bytes` rather than exact match.
Relax subgraph byte constraint to `required_bytes <= bytes` rather than exact match.

This has been an error raised for some issues [github example](https://github.com/tensorflow/tensorflow/issues/14929).

If the required bytes are covered by the current model, there is no need to raise an error due to exact size mismatch on user's side.
