[clang] [CIR][AArch64] Lower BF16 vduph lane builtins (PR #185852)

[Jiahao Guo via cfe-commits]

E00N777 wrote:

> > Hi @andykaylor , this PR has been approved by @banach-space . As a first-time contributor, I'm not sure about the typical merge timeline — could you help merge it when you get a chance? Thank you!
> 
> @E00N777 , you have addressed Andy's comments and I can land this for you, but have just noticed a minor thing that's not needed in your tests. Would you be able to update that? Thanks!

@banach-space 
No problem！

https://github.com/llvm/llvm-project/pull/185852