Fix the check

mlx/backend/cuda/reduce/col_reduce.cu

@@ -338,7 +338,7 @@ void col_reduce(
 
   // Small col reduce with a single or contiguous reduction axis
   if (args.non_col_reductions == 1 && args.reduction_size <= 32 &&
-      args.reduction_stride % 4 == 0) {
+      args.reduction_stride % (16 / in.itemsize()) == 0) {
     col_reduce_small(
         encoder, in, out, reduce_type, axes, plan, std::move(args));
     return;