you need to add the following entries in pom.xml.
<properties>
<liferay.theme.parent>classic</liferay.theme.parent>
<liferay.theme.type>vm</liferay.theme.type>
</properties>
you can give parent theme as _styled,_unstyled or classic depending upon your requirement.
In liferay-look-and-feel.xml we specify themeId , version etc. While plugin development using maven, we have to specify these values in pom.xml. So there is no need of liferay-look-and-feel.xml