[WIP][fx2trt] Replacing fp16 and int8 mode with enum type (#74338)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/74338
X-link: https://github.com/pytorch/fx2trt/pull/24
X-link: https://github.com/pytorch/benchmark/pull/805
Test Plan: CI
Reviewed By: jasonjk-park
Differential Revision: D34929680
fbshipit-source-id: 8d693ffdfc28d12f5b88aba170da87b192c5e5a2
(cherry picked from commit 45d3dcdf03416c0de4eecf85827132074cb50528)
