removing repeated docstring for param mask

Author: Giulio Zizzo

art/attacks/evasion/projected_gradient_descent/projected_gradient_descent_tensorflow_v2.py

@@ -239,9 +239,6 @@ def _generate_batch(
                      perturbed.
         :param eps: Maximum perturbation that the attacker can introduce.
         :param eps_step: Attack step size (input variation) at each iteration.
-        :param mask: An array with a mask broadcastable to input `x` defining where to apply adversarial perturbations.
-                     Shape needs to be broadcastable to the shape of x and can also be of the same shape as `x`. Any
-                     features for which the mask is zero will not be adversarially perturbed.
         :return: Adversarial examples.
         """
         adv_x = x