[llvm] [AArch64] Combine separate vector and scalar tablegen SDNode record for AArch64ISD::REV16. NFC (PR #125614)

[David Green via llvm-commits]

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

I believe we should be safe given we only generate nodes with the types that are valid, and the classes are different. We can always add a new node if we need.

https://github.com/llvm/llvm-project/pull/125614