Remove unused field in jit script module deserializer (#15439)
Summary:
A little bit clean up.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15439
Reviewed By: zrphercule
Differential Revision: D13532015
Pulled By: houseroad
fbshipit-source-id: 2fb1e01fc28549c7e78af6c65ee68339950bc7da
