[llvm] [RISC-V] Do not emit cm.popret[z] with zicfiss (PR #196267)

[Nemanja Ivanovic via llvm-commits]

nemanjai wrote:

> In case the reproducer helps.
> 
> [floattidf-371435.sh](https://github.com/user-attachments/files/30479581/floattidf-371435.sh) [floattidf-371435.c](https://github.com/user-attachments/files/30479585/floattidf-371435.c)

I'll have a look. Thanks for providing the repro.

https://github.com/llvm/llvm-project/pull/196267