[llvm] [AMDGPU][True16][CodeGen] update wwm reg sorting check condition (PR #135053)

[Christudasan Devadasan via llvm-commits]

cdevadas wrote:

> > Please add a test
> 
> I checked the wwm reg related test and it seems I could not find any thing that test for the sorting of the reserved reg. Hi @cdevadas are you comfortable with merging this as it, or is there a recommended test that I can look into? Thanks for the hint!

This change you added to skip the 16-bit wwm-regs. Did you happen to encounter any errors earlier? If yes, add a test for the 16-bit register - nothing to be added for the 32-bit wwm-reg case. 

https://github.com/llvm/llvm-project/pull/135053