Tacotron2 1.9.0 bugfixes
# What does this PR do ?

Update Tacotron2 training tutorial and config to work with r.1.9.0

**Collection**: TTS

# Changelog 
- Updated 44kHz config to use TTSDataset (now matches with 22kHz config)
- Added file downloads necessary for training to the Tacotron2 notebook
- Minor bugfix to avoid device mismatch during training for the notebook

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