This PR handles`v_pk_fmac_f16` inline constant encoding/decoding differences between pre-GFX11 and GFX11+ hardware. - Pre-GFX11: fp16 inline constants produce `(f16, 0)` - value in low 16 bits, zero in high. - GFX11+: fp16 inline constants are duplicated to both halves `(f16, f16)`. Fixes #94116.