[llvm] [RISCV] Don't increase vslide or splat vl if +minimize-vl is present (PR #147089)

[Pengcheng Wang via llvm-commits]

https://github.com/wangpc-pp approved this pull request.

LGTM, but does it really make big difference for this case?

https://github.com/llvm/llvm-project/pull/147089