[clang] [llvm] [RISCV] Make M imply Zmmul (PR #95070)

[Craig Topper via llvm-commits]

topperc wrote:

We intentionally didn't do this because it makes LLVM not work with binutils that doesn't know about Zmmul. Maybe enough time has  passed that it is no longer an issue?

https://github.com/llvm/llvm-project/pull/95070