[llvm] [RISCV] Fixed redundant add instructions generated during the fold of vscale add in rvv. (PR #225266)

[Pengcheng Wang via llvm-commits]

wangpc-pp wrote:

Please use `llvm/utils/update_llc_test_checks.py` to update all these failed tests. @FoolgryGamer 

https://github.com/llvm/llvm-project/pull/225266