[llvm] [RISC-V] Fix incorrect epilogue_begin (PR #120623)

[Eli Friedman via llvm-commits]

efriedma-quic wrote:

FYI, it's not really helpful to wait from midnight US time until early morning US time; probably nobody saw your first message before you merged.  If you actually want to give people time to comment, please give at least 24 hours.  (In this case, I don't think you needed to wait anyway, so it's fine.)

https://github.com/llvm/llvm-project/pull/120623