Update SiFive submodules to CHIPS fork

[michael-etzkorn]

SiFive versions of repos will no longer be actively maintained so they've been transferred over to Chipsalliance.

Related PRs / Issues:

#1171

Type of change:

• Bug fix
• New feature
• Other enhancement

Impact:

• RTL change
• Software change (RISC-V software)
• Build system change
• Other

Contributor Checklist:

• Did you set main as the base branch?
• Is this PR's title suitable for inclusion in the changelog and have you added a changelog:<topic> label?
• Did you state the type-of-change/impact?
• Did you delete any extraneous prints/debugging code?
• Did you mark the PR with a changelog: label?
• (If applicable) Did you add documentation for the feature?
• (If applicable) Did you add a test demonstrating the PR?

• (If applicable) Did you mark the PR as Please Backport?

[michael-etzkorn]

I can't add a changelog label, but the label would be omit.

[michael-etzkorn]

I'll fix the CI run commit check for this over the weekend, but feel free to scoop me to that.

[michael-etzkorn]

@jerryz123 This should now pass the check-commit CI job. fpga-shells' main branch is now named main and I've updated the script to reflect that.

[abejgonzalez]

LGTM