This is confusing me. Looks like you have two different things mixed up.
The context param is for the ContextLoaderListener creating an ApplicationContext for just the middle tier beans. The mvc-dispatcher-servlet.xml is following the naming convention of the file that the DispatcherServlet looks for to create the other ApplicationContext that is just for the web layer beans.
In a Spring MVC app you should have 2 ApplicationContexts. One for middle tier beans using ContextLoaderLister and one for the web layer beans using DispatcherServlet. To tell the DispatcherServlet where its config file is, you use the init-param tag in the <servlet> tag in your web.xml