[llvm] [RISCV] Fix missing scaling by LMUL in cost model (PR #73342)

[Shih-Po Hung via llvm-commits]

arcbbb wrote:

> @arcbbb is part of this now covered by your recent work?

Thanks for mentioning me in this thread!
The intrinsic stepvector and smin/smax/umin/umax are covered in #87301 and #87245.
And my next target would be to implement getCmpSelInstrCost with getRISCVInstructionCost.

https://github.com/llvm/llvm-project/pull/73342