[llvm] [ARM][NEON] Add constraint to vld2 Odd/Even Pseudo instructions. (PR #79287)

[Alfie Richards via llvm-commits]

AlfieRichardsArm wrote:

I have updated the tests as suggested

I checked and the variants like `VLDQQWBfixedPseudoConstrained` with `VLD2DUPq32OddPseudoWB_fixed` are tested in `vlddup-update.ll` if that was what you meant?

https://github.com/llvm/llvm-project/pull/79287