Add messages to require statements in Math (backport #3385)

[mergify]

This is an automatic backport of pull request #3385 done by Mergify.
Cherry-pick of 88fecfc has failed:

On branch mergify/bp/3.5.x/pr-3385
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You are currently cherry-picking commit 88fecfc1c.
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Unmerged paths:
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	both modified:   src/main/scala/chisel3/util/Math.scala

no changes added to commit (use "git add" and/or "git commit -a")

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/github/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

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