Replace AT_ASSERTM with TORCH_CHECK (#21267)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/21267
Replace AT_ASSERTM with TORCH_CHECK: AT_ASSERTM is deprecated.
Not sure when ```AT_ASSERT``` is dprecated with some new TORCH ASSERT function.
Reviewed By: zafartahirov
Differential Revision: D15599242
fbshipit-source-id: 23f21a9a23dc3c147dc817e6d278066d0832e08d
