torchdynamo: add linear eltwise fusion kernel (#85622)
Support fusion of linear with:
- relu
- sigmoid
- tanh
- hardswish
- leaky_relu
- hardtanh
- gelu
Pull Request resolved: https://github.com/pytorch/pytorch/pull/85622
Approved by: https://github.com/EikanWang, https://github.com/jansel
