[llvm] [RISCV][Scheduler] Add scheduling definitions for 128-bit Zfa instructions (PR #140003)

[Pengcheng Wang via llvm-commits]

https://github.com/wangpc-pp approved this pull request.

LGTM but please wait for a few days.
I need more eyes on the naming and the approach to fix the combination of Zfa and other floating-point extensions. @topperc @lenary 

https://github.com/llvm/llvm-project/pull/140003