[llvm] [AArch64] Use unsigned variant of `<s|u>addv_64` SVE vector reduction intrinsic for 64 bit values (PR #157418)

[David Green via llvm-commits]

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

Thanks for putting together a fix for this. LGTM

https://github.com/llvm/llvm-project/pull/157418