[llvm] [RISCV] Recommit "Expand vp.stride.load to splat of a scalar load." (PR #98579)

[Yeting Kuo via llvm-commits]

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yetingk wrote:

I add the test and I also add the hasOptimizedZeroStrideLoad check back.

https://github.com/llvm/llvm-project/pull/98579