add audio-model feature

templates/libvirt/xen.xml

@@ -188,6 +188,9 @@
                     {% endif %}
                     />
                 <input type="tablet" bus="usb"/>
+                {% if vm.features.check_with_template('audio-model', False) %}
+                    <sound model="{{ vm.features.check_with_template('audio-model', False) }}"/>
+                {% endif %}
                 {% if vm.features.check_with_template('video-model', 'vga') != 'none' %}
                     <video>
                         <model type="{{ vm.features.check_with_template('video-model', 'vga') }}"/>