[llvm] [SelectionDAG] Use correct result type in visitEXTRACT_VECTOR_ELT (PR #148707)

[Da Li 李达 via llvm-commits]

dlee992 wrote:

> Do you have a test case?

I don't have one right now. I need to make up one with public targets, but I'm unfamiliar with public targets yet. (or anyone can help? Thanks!)

This PR is extremely similar with [this regression fix](https://github.com/llvm/llvm-project/commit/c268a3f0934c625238a1391f6da55c10fecda9de#diff-851c90a60f1be0547bc1b8af1eba5b11de418c7b0851a35ee0dcdd03425aa62e), so also cc @arsenm .

https://github.com/llvm/llvm-project/pull/148707