message: fix subgroup size in 16
diff: local PARAMS = {
  metal: {
  CACHE_WIDTH: 64,
  - MAX_MEM: [1000, 3200],
  - SUBGROUP_SIZES: [8, 16],
  + MAX_MEM: [3000],
  + SUBGROUP_SIZES: [16],
  GLOBAL_MEM_LAT: 420,
  LOCAL_MEM_LAT: 125,
  },
  