[llvm] [RISCV] Add hasSideEffects = true to ReadFRM (PR #139864)

[Pengcheng Wang via llvm-commits]

wangpc-pp wrote:

> > Do you have a case to show the miscompile?
> 
> Sure, here you go: https://godbolt.org/z/Kx1qsTeGY

Then please add a .ll test and precommit it.

https://github.com/llvm/llvm-project/pull/139864