Add ethernet support

[arturum1]

• Update py2hwsw, enabling ethernet support on SoCLinux.
  By default ethernet interface is enabled and used to speed up file transfers.
  If needed, set USE_ETHERNET=0 environment variable to disable ethernet and use only serial interface for file transfers.
• Update README with information and instructions about the ethernet interfaces.

[arturum1]

Related to PR IObundle/py2hwsw#391

[Copilot]

Pull Request Overview

This PR adds ethernet support to the SoCLinux template by updating the py2hwsw dependency and modifying the build system. By default, ethernet is enabled to accelerate file transfers, but can be disabled using the USE_ETHERNET=0 environment variable for serial-only communication.

• Updated py2hwsw commit hash to version supporting ethernet functionality
• Enhanced Makefile to handle ethernet configuration via environment variables
• Added comprehensive documentation for ethernet setup, simulation, and troubleshooting

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
default.nix	Updates py2hwsw commit hash and SHA256 to newer version with ethernet support
README.md	Adds ethernet documentation including setup instructions, simulation requirements, and troubleshooting
Makefile	Refactors parameter handling to support USE_ETHERNET and other system configuration options

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