[llvm] [RISCV] Change RISCVMCExpr::VK_RISCV_None to RISCVMCExpr::VK_None (PR #131774)

[Simon Pilgrim via llvm-commits]

https://github.com/RKSimon approved this pull request.

LGTM - please either get this committed asap or revert #130779 as you are breaking most buildbots at the moment

https://github.com/llvm/llvm-project/pull/131774