Fix single GPU training issue + change deprecated Lightning args
# What does this PR do ?

Critical: Fix single GPU training issue
Also, change deprecated Lightning args
**Collection**: Core + most others

# Changelog 
The PR changes:
`num_process` --> `devices`/`num_devices`
`num_gpus` --> `num_devices`

**PR Type**:
- [ ] New Feature
- [x] Bugfix
- [ ] Documentation


