[llvm] [AArch64] Improve lowering of truncating uzp1 (PR #82457)

[Usman Nadeem via llvm-commits]

UsmanNadeem wrote:

> I see two Aarch64 tests consistently failing on the bot after this change: https://lab.llvm.org/buildbot/#/builders/272/builds/11141

I fixed those in https://github.com/llvm/llvm-project/commit/79cd2c0bb9acb4685094d6b3bf21c758aa51d3df


https://github.com/llvm/llvm-project/pull/82457