[clang] [llvm] Revert "[RISCV] Relax march string order constraint" (PR #79976)

[Mehdi Amini via cfe-commits]

joker-eph wrote:


- Reverting a change that way costs me 3 clicks: it is the lowest cost on me to fix the CI.
- We likely want people to be able to use the pre-merge checks independently of the reviews: you're way of tying "opening a PR" to some expectations (that aren't clear to me) seems to go against this. 




https://github.com/llvm/llvm-project/pull/79976