[tensorexpr] Fix the buf size of discontiguous tensors (#69657)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/69657
Test Plan: Imported from OSS
Reviewed By: ZolotukhinM
Differential Revision: D32974473
Pulled By: huiguoo
fbshipit-source-id: 52dcd13d0ad7f7e4f1beb69dcaabc8ceb386ffca
