[llvm] IR: Allow vector type in atomic load and store (PR #117625)

[via llvm-commits]

jofrn wrote:

Verifier checks can be disabled with `-disable-verify`, which already permits the lowering of atomic load/store with vector type in multiple targets, as such, some are already implemented. Permitting the type in Verifier/IR is different than a single implementation of the lowering.

https://github.com/llvm/llvm-project/pull/117625