[llvm] [AArch64] Lower partial add reduction to udot or svdot (PR #101010)

[Paul Walker via llvm-commits]

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

Mostly superficial comments with the removal of `WideType` (assuming you agree that it is redundant) being the only one I really care about. Otherwise the patch looks good to me.

https://github.com/llvm/llvm-project/pull/101010