[llvm] [AArch64][GlobalISel] Fix incorrect codegen for FPR16/FPR8 to GPR copies (PR #171499)

[via llvm-commits]

llvmbot wrote:

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>> Has this been backported as a fix to earlier releases? Apologies if that's obvious, I'm not familiar with the process here.
>
>No. If you want to add it to the release, you need to set the release milestone and use /cherry-pick to attempt auto-applying to the branch 

Error: Command failed due to missing milestone.

https://github.com/llvm/llvm-project/pull/171499