Add the nc:config wrapper for svlan_creation pyformat

<?xml version="1.0" encoding="UTF-8"?>

<nc:config xmlns:nc="urn:ietf:params:xml:ns:netconf:base:1.0">

<dot1q:bridges xmlns:dot1q="urn:ieee:std:802.1Q:yang:ieee802-dot1q-bridge">

    <dot1q:bridge>

        <dot1q:name>{bridge_name}</dot1q:name>

        </dot1q:component>

    </dot1q:bridge>

</dot1q:bridges>

</nc:config>