Recent nvidia hardware has a native instruction for
nir_intrinsic_vote_ieq but not for nir_intrinsic_vote_feq. So, split
this boolean into two so we can contol the lowering separately for each
instruction.
Reviewed-by: Faith Ekstrand <faith.ekstrand@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/35778>