aco/gfx11+: disable v_pk_fmac_f16_dpp

Public docs are apparently wrong: https://github.com/llvm/llvm-project/pull/79598#issuecomment-1933988048



Cc: mesa-stable

Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Part-of: <mesa/mesa!27533>
(cherry picked from commit e927c500)