YOLOX: Evaluation script is enabled for HPU

[dsmertin]

Description

The yolox/tools/eval.py script has been enabled for HPU:

• It can be run on 1 card or in distributed mode;
• It supports BF16 type;
• Added --cpu-post-processing and --warmup_steps options;
• Implemented new post-processing which works faster than original;
• Eager mode is enabled;
• List of performance metrics has been expanded with latency and throughput.

The yolox/README.md has been accordingly updated.

Type of changes

• [ ] Documentation update
• [ ] Bug fix (changes which fix an issue)
• [x] Others: Functionality extension

Tests

These changes have been tested on Gaudi 2 in single card and multi cards modes. Accuracy didn't change. All new command-lines introduced in the updated README.md was tested as well.

Checklist

• [x] I agree with the Developer Certificate of Origin.
• [x] My code conforms to the following coding guidelines:
  • [x] Use Python 3
  • [ ] Python code follows PEP 8 Coding Styles
• [x] I have performed a self code review.
• [x] I have made corresponding changes to the documentation.
• [ ] I have added tests that prove my fix is effective or that my feature works.