Try using this code:
<?php
class WorkplaceAllController extends ModuleAdminController
{
public function init()
{
parent::init();
}
public function initContent()
{
$module_name = 'workplace';
parent::initContent();
if(version_compare(_PS_VERSION_, '1.7', '>')) {
$this->setTemplate('module:' . $module_name . '/views/templates/front/all17.tpl');
}else {
$this->setTemplate('all.tpl');
}
}
}
For Prestashop 1.6.x.x: template all.tpl located here: /modules/workplace/views/templates/front/all.tpl
For Prestashop 1.7.x.x: template all.tpl located here: /modules/workplace/views/templates/front/all17.tpl