[llvm] [AMDGPU] fix SIPeepholeSDWA optimization for fp16 (PR #109395)

[Pankaj Dwivedi via llvm-commits]

PankajDwivedi-25 wrote:

This is what I'm seeing in the assembly 
"v_add_f16_sdwa v16, v2, v4 dst_sel:DWORD dst_unused:UNUSED_PAD src0_sel:DWORD src1_sel:WORD_1" which corrosponds to v_add_f16_adwa

https://github.com/llvm/llvm-project/pull/109395