[llvm] [AArch64][Isel] Add lowering for fixed-width interleave3 (PR #192677)

[Paul Walker via llvm-commits]

https://github.com/paulwalker-arm approved this pull request.

Thanks Matt. A couple of requests but otherwise this looks good to me. I'll re-review if it turns out you need code changes, but I'm not expecting this to be necessary.

https://github.com/llvm/llvm-project/pull/192677