[fx2trt][easy] Replace all network.add_activation() call with helper function (#68676)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/68676
As the title, the helper functions handles setting layer name. We would want to use those helper functions whenever possible.
Test Plan: CI
Reviewed By: wushirong
Differential Revision: D32571061
fbshipit-source-id: 4a191f0085c0b3965dc02d99bb33de21973d565d
