[llvm] [RISCV][TTI] Model the cost of insert/extractelt when the vector split into multiple register group and idx exceed single group. (PR #118401)

[Philip Reames via llvm-commits]

preames wrote:

> CodeGen for extract/insert element exceed single register group. https://godbolt.org/z/r1zKEoK1P

Thank you for including this.  It made spot checking the codegen much simpler.  

https://github.com/llvm/llvm-project/pull/118401