[llvm] [GlobalISel] Only narrow IEEE half in narrowScalarFPTOI (PR #223615)

[Kane Wang via llvm-commits]

ReVe1uv wrote:

> Hello - The code change sounds fine, but shouldnt really be reached by a well behaving target. The tests are maybe a bit much for something that shouldnt be ran - is TypedFloatMatchesUntypedScalar necessary to add or can we keep it more simple?

Fair point — dropped TypedFloatMatchesUntypedScalar. The wildcard matching it was pinning is already covered by the untyped s16 case in NarrowFPTOIExtLLT, so it wasn't really adding anything.

https://github.com/llvm/llvm-project/pull/223615