Re-Cherry-pick LLVM PR 127844 (#20035)

[MLIR] Fix rewrite of ops with vector operands to LLVM on GPU.

llvm/llvm-project#127844

Previously cherry-picked in #20031
and then dropped in #20015.

Needed by the just-merged #19969.

Signed-off-by: Benoit Jacob <[email protected]>

Author: bjacob