flatten operation (resnet50) (#61265)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/61265
Test Plan: Imported from OSS
Reviewed By: jamesr66a
Differential Revision: D29626383
Pulled By: migeed-z
fbshipit-source-id: 107769fc14f1fad295a93a10e84235f25ae17357
