[llvm] [Clang][Codegen] fix vector data by modifying VMVN (PR #105913)

[via llvm-commits]

Zhenhang1213 wrote:

> I think I would fold this into #105519. If this is not affecting any tests then the might not be any big endian test coverage for them at the moment. I've added a few extra tests in [9f82f6d](https://github.com/llvm/llvm-project/commit/9f82f6daa5e470652f4ffced628547d0c24aac2c)

I rebased it and modified the failed tests, this pr is just a reference, and I've collapsed it into #105519

https://github.com/llvm/llvm-project/pull/105913