fix expression must have a constant value

tensorflow\tensorflow/core/framework/tensor_shape.h(468): error : expression must have a constant value
    static_assert(NDIMS <= TensorShape::MaxDimensions(), "Too many dimensions");
                  ^
tensorflow\tensorflow/core/framework/tensor_shape.h(468): note: constexpr function function "tensorflow::TensorShapeBase<Shape>::MaxDimensions [with Shape=tensorflow::TensorShape]" (declared at line 195) is not defined
    static_assert(NDIMS <= TensorShape::MaxDimensions(), "Too many dimensions");
                                        ^