[llvm] RISCVAsmParser: Don't treat operands with relocation specifier as parse-time constants (PR #133377)

[Alex Bradbury via llvm-commits]

asb wrote:

Happy to defer to Sam's review of the code, but I wanted to give an explicit LGTM on the direction and to say thank you for taking the time to look at how we clean up our MC code. Writing this evaluation code was a useful exercise at the time, but I agree it's unnecessary complexity at this point.

https://github.com/llvm/llvm-project/pull/133377