<ul id="device-cat">
<?php foreach ($data as $d1) : ?>
    <li><span class="cat1"><?= $d1['text'] ?></span>
        <?php if ($d1['children']) : ?>
            <ul>
                <?php foreach ($d1['children'] as $d2) : ?>
                <li><input type="checkbox" name="deviceCat[]" value="<?= $d2['id'] ?>" <?php if ($d2['checked'])  echo 'checked' ?> >  <?= $d2['text'] ?> </li>
                <?php endforeach; ?>
            </ul>
        <?php endif; ?>
    </li>
<?php endforeach; ?>
</ul>

<style>
    #device-cat {
        list-style: none;
        height: 200px;
        overflow-y: scroll;
        width: 300px;
        background-color: #f5f5f5;
    }
    #device-cat ul {
        list-style: none;
    }
    #device-cat li {
        line-height: 30px;
    }
</style>