[HiFiGAN] Missing class variable in model ResBlock2

[itakatz]

Related to PyTorch/SpeechSynthesis/HiFiGAN

Describe the bug
The class variable lrelu_slope is used in the class method forward but it is not defined. which raises an exception if HiFiGAN is trained with a parameter --resblock 2. The variable is referenced here:

DeepLearningExamples/PyTorch/SpeechSynthesis/HiFiGAN/hifigan/models.py

Line 130 in d56fe70

xt = F.leaky_relu(x, self.lrelu_slope)

To Reproduce
Train HiFiGAN using the regular script (scripts/train.sh), adding the input parameter --resblock 2

Expected behavior
Training should run with no errors

Solution
Define the class variable in the __init__ method, similarly as in class ResBlock1, that is add:
self.lrelu_slope = LRELU_SLOPE

Environment

• Container version: nvcr.io/nvidia/pytorch:22.12-py3
• GPUs in the system: 8X A40
• CUDA driver version: 520.61.05