net/mlx5e: Cleanup MACsec uninitialization routine

The mlx5e_macsec_cleanup() routine has NULL pointer dereferencing if mlx5
device doesn't support MACsec (priv->macsec will be NULL).

While at it delete comment line, assignment and extra blank lines, so fix
everything in one patch.

Fixes: 1f53da6 ("net/mlx5e: Create advanced steering operation (ASO) object for MACsec")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec.c

@@ -1846,25 +1846,16 @@ int mlx5e_macsec_init(struct mlx5e_priv *priv)
 void mlx5e_macsec_cleanup(struct mlx5e_priv *priv)
 {
 	struct mlx5e_macsec *macsec = priv->macsec;
-	struct mlx5_core_dev *mdev = macsec->mdev;
+	struct mlx5_core_dev *mdev = priv->mdev;
 
 	if (!macsec)
 		return;
 
 	mlx5_notifier_unregister(mdev, &macsec->nb);
-
 	mlx5e_macsec_fs_cleanup(macsec->macsec_fs);
-
-	/* Cleanup workqueue */
 	destroy_workqueue(macsec->wq);
-
 	mlx5e_macsec_aso_cleanup(&macsec->aso, mdev);
-
-	priv->macsec = NULL;
-
 	rhashtable_destroy(&macsec->sci_hash);
-
 	mutex_destroy(&macsec->lock);
-
 	kfree(macsec);
 }