Adding a flag to enable CPU fusion in benchmarks (#48612)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/48612
Test Plan: python -m benchmarks.tensorexpr --device cpu --mode fwd --jit_mode trace --cpu_fusion element
Reviewed By: heitorschueroff
Differential Revision: D26548643
Pulled By: navahgar
fbshipit-source-id: adb537818d77c9b6b0fe434ae6d963a5f348ad24
