[llvm] [AArch64][NFC] NFC for const vector as Instruction operand (PR #116790)

[David Green via llvm-commits]

https://github.com/davemgreen approved this pull request.

I have been a little sceptical about costing constants with how they are currently represented in llvm and how often they can be "free". They can certainly be more expensive at times, looking forward to being proved incorrect about it.

The tests LGTM.

https://github.com/llvm/llvm-project/pull/116790