[llvm] [RISCV] Simplify the insertelement 0, x, x in vector.reduce with an initial value to 0 (PR #193709)

[Pengcheng Wang via llvm-commits]

https://github.com/wangpc-pp commented:

Would it be better if we do this transformation in vectorizer?

https://github.com/llvm/llvm-project/pull/193709