[llvm] [AMDGPU] Use RTZ for newer fp16 interp instructions (PR #86235)

[Georg Lehmann via llvm-commits]

DadSchoorse wrote:

Why set the rounding mode when there are V_INTERP_P10_RTZ_F16_F32 and V_INTERP_P2_RTZ_F16_F32 which always use rtz?

https://github.com/llvm/llvm-project/pull/86235