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

[Alex Bradbury via cfe-commits]

asb 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.

Thanks! Sorry I wasn't specific about this, but we need a Clang release note as well.

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