[llvm] AMDGPU: Use pattern to select instruction for intrinsic llvm.fptrunc.round (PR #105761)

[Thorsten Schütt via llvm-commits]

tschuett wrote:

I couldn't find neither the old nor the new name of FPTRUNC_ROUND in https://llvm.org/docs/GlobalISel/GenericOpcode.html.

https://github.com/llvm/llvm-project/pull/105761