Fix a bug in qconv (#21294)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/21294
Returned output tensor wasn't of correct shape
Reviewed By: zafartahirov
Differential Revision: D15605081
fbshipit-source-id: f79a9d5b93b8b97e79c09411b9dc681987a61e44
