[llvm] [clang] [clang][RISCV] Change default abi with f extension but without d extension (PR #73489)

[Jianjian Guan via cfe-commits]

jacquesguan wrote:

> I think the conclusion from the LLVM sync-up call was that everyone happy to move in this direction, so please add the release note and we can do a final review. Thanks!

Done, added release note.

https://github.com/llvm/llvm-project/pull/73489