[llvm] [AMDGPU][LibCallSimplify] Use target type's float-semantics in `ConstantFP::get` (PR #213721)

[Juan Manuel Martinez Caamaño via llvm-commits]

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jmmartinez wrote:

I'm tempted to move this just before the `if (hasTwoResults) {` and then remove the trivially true `assert(FInfo.getId() == AMDGPULibFunc::EI_SINCOS && "math function with ptr arg not supported yet");`.

https://github.com/llvm/llvm-project/pull/213721