[clang] AMDGPU: Remove cvt-pknorm-vop3-insts from feature map (PR #213615)

[Matt Arsenault via cfe-commits]

arsenm wrote:

> Are we missing the change that actually removes it from the feature map ?

First attempt did the removal, second attempt only had the tests 

https://github.com/llvm/llvm-project/pull/213615