[llvm] [RISCV][NFC] Move Zawrs implementation to RISCVInstrInfoZawrs.td (PR #76940)

[Alex Bradbury via llvm-commits]

https://github.com/asb approved this pull request.

LGTM. I think it's not necessarily the case that every extension should have it's own file, but Zawrs would better belong in RISCVInstrInfoA or RISCVInstrInfoZa.td I think if we felt it didn't deserve its own file.

https://github.com/llvm/llvm-project/pull/76940