Fix System.IO.Port declaration

[josesimoes]

Description

• Fix System.IO.Port declaration.

Motivation and Context

How Has This Been Tested?

Screenshots

Types of changes

• Improvement (non-breaking change that improves a feature, code or algorithm)
• 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 change)
• Config and build (change in the configuration and build system, has no impact on code or features)
• Dependencies (update dependencies and changes associated, has no impact on code or features)
• Unit Tests (work on Unit Tests, has no impact on code or features)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[nfbot]

@josesimoes there are issues with the code style on the source files.

⚠️Couldn't submit a PR with the fixes against your repo.⚠️

Please merge the changes from https://github.com/nanoframework/nf-interpreter/tree/nfbot/clang-format-fix/001f474b-9b32-4c7c-8438-92d92a94eb43.