function mymodule_form_alter(&$form, &$form_state, $form_id) {
  if(strpos($form_id, 'uc_product_add_to_cart') !== FALSE){
    $form['qty']['#title'] = t('');
  }
}

if(strpos($form_id, 'uc_product_add_to_cart') !== FALSE){
  $view = $form_state['view'];
  if ($view->name == 'my_view_machine_name') {
    $form['qty']['#title'] = t('');
  }
}