[clang-tools-extra] [NFC][CodeGen] Create method to clear registers (PR #66958)

[Bill Wendling via cfe-commits]

bwendling wrote:

> I'm assuming there are other targets that would benefit from being converted as well? Not asking you to do it, just wondering what the best way to get it done is.

Yeah, the other platforms can implement this when / if they need it. It's really just a convenience function that I'm planning on using soon-ish.

https://github.com/llvm/llvm-project/pull/66958