inductor: don't assert error when do cpu fx fusion for training mode (#93837)
This PR will do:
1. skip CPU fx fusion for training mode.
2. skip Linear packed when input dim<2.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/93837
Approved by: https://github.com/jgong5, https://github.com/desertfire, https://github.com/jansel
