[llvm] [RISCV] Expand vp.stride.load to splat of a scalar load. (PR #98140)

[Yeting Kuo via llvm-commits]

yetingk wrote:

> No plans here! Would you still plan on landing this PR before vp.splat is added?

I plan to wait new comments of this PR for around 12 hours.

https://github.com/llvm/llvm-project/pull/98140