fixed argument error in demo notebook

Signed-off-by: Ajay Sarjoo <ajay.sarjoo@outlook.com>

Author: asarj

notebooks/output_smoothmix_cifar10.ipynb

@@ -314,7 +314,6 @@
     "    alpha=alpha_1,\n",
     "    scale=sigma_1, \n",
     "    num_noise_vec=num_noise_vec,\n",
-    "    train_multi_noise=True,\n",
     "    attack_type=\"PGD\",\n",
     "    num_steps=num_steps,\n",
     "    warmup=warmup,\n",
@@ -353,7 +352,6 @@
     "    alpha=alpha_2,\n",
     "    scale=sigma_2, \n",
     "    num_noise_vec=num_noise_vec,\n",
-    "    train_multi_noise=True,\n",
     "    attack_type=\"PGD\",\n",
     "    num_steps=num_steps,\n",
     "    warmup=warmup,\n",