<div class="collapse navbar-collapse justify-content-end" id="navbarSupportedContent">
  <?php
      if (has_nav_menu('primary_navigation')) :
           wp_nav_menu([ 'container'=> false,
                          'theme_location' => 'primary_navigation',
                          'menu_class' => 'navbar-nav ml-auto mobile']);
            endif;
   ?>

 </div>