Update x/sys and x/net modules to support Risc-V

[carlosedp]

Signed-off-by: CarlosEDP me@carlosedp.com

Description

Updating projects using libraries that were recently updated to support Risc-V architecture.

Go upstream work is tracked on: golang/go#27532

Risc-V software support tracker on https://github.com/carlosedp/riscv-bringup

Types of changes

• 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)

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've read the CONTRIBUTION guide
• I have signed-off my commits with git commit -s
• I have added tests to cover my changes.
• All new and existing tests passed.

[alexellis]

Approved

[alexellis]

Thank you @carlosedp, merged 👍