Sorry I overlooked one line of ListConverter documentation.. I missed feeding the ListConverter with the original list like mentioned below.
<o:converter converterId="omnifaces.ListConverter" list="#{mybean.lstStatus}" />
I got this worked by adding above line of code.
Final xhtml is going to look like below..
<p:autoComplete id="iterator3" value="#{mybean.objLuStatus}" forceSelection="true"
dropdown="true" var="entity"
itemLabel="#{entity.strDescColVal}"
placeholder="----- Select One -----" itemValue="#{entity}"
completeMethod="#{mybean.completeList}">
<f:ajax render="selected_status" />
<o:converter converterId="omnifaces.ListConverter" list="#{mybean.lstStatus}" />
</p:autoComplete>
Thank you to omnifaces team for providing such a useful utility...