Description

This PR fixes two compatibility issues in the Hygon backend.

First, it improves the package path resolution for transformer_engine_hygon. In some environments, importlib.util.find_spec() may return a ModuleSpec with origin=None, which causes the previous implementation to fail when resolving the package directory. This PR adds a fallback to submodule_search_locations and reports an error if neither source is available.

Second, transformer_engine_hygon currently does not implement the multi_tensor_scale_tensor API (available in upstream NVIDIA TransformerEngine v2.14). This PR replaces the unsupported call with the existing multi_tensor_scale implementation by extracting the scalar value from the input tensor, preserving equivalent functionality on the Hygon backend.

Fixes # (issue)

Type of change

• Documentation change (change only to the documentation, either a fix or a new content)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Infra/Build change
• Code refactoring

Changes

Please list the changes introduced in this PR:

• Improve transformer_engine_hygon package path resolution by handling the case where ModuleSpec.origin is None.
• Add a fallback to submodule_search_locations when locating Hygon backend libraries.
• Return a descriptive error when the package path cannot be determined.
• Replace the unsupported multi_tensor_scale_tensor call with multi_tensor_scale by converting the scale tensor to a scalar value.
• Add comments explaining the compatibility workaround for the Hygon backend.

Checklist:

• I have read and followed the contributing guidelines
• The functionality is complete
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes