[llvm] [AArch64][SVE] Add partial reduction SDNodes (PR #117185)

[James Chesterman via llvm-commits]

JamesChesterman wrote:

This work is being split into separate Pull Requests and is being done differently.
See here for first PR:
https://github.com/llvm/llvm-project/pull/125207


https://github.com/llvm/llvm-project/pull/117185