[llvm] [RISCV] Fold extract_vector_elt of a load into the scalar load (PR #76151)

[Liao Chunyu via llvm-commits]

ChunyuLiao wrote:

1. Invert if
2. Delete the int variable, merge it into the PtrOff variable.
Thanks.

https://github.com/llvm/llvm-project/pull/76151