What you have is a layered architecture where you have decoupled your presentation layer with persistence layer. When you implement an MVC, you need to present your view using
JSP, FreeMarker, Velocity etc as well. You servlet should act only as a controller and should not be responsible for preparing the view for your request. It should dispatch the request to a JSP or appropriate view template after getting data from a Model (in your case DAO layer).
As for package structure, you can segregate them either by layer or by functionality and layer.
Layerd Package Structure
com.xyx.web.servlet.LoginServlet
com.xyx.web.servlet.QueryServlet
com.xyx.web.servlet.RegisterServlet
com.xyx.persistence.dao.LoginDao
com.xyx. persistence.dao.QueryDao
com.xyx.persistence.dao.RegisterDao
Segregating based on functionality and layer
com.xyx.login.web.servlet.LoginServlet
com.xyx.login.persistence.dao.LoginDao
com.xyx.query.web.servlet.QueryServlet
com.xyx.query.persistence.dao.QueryDao
com.xyx.register.web.servlet.RegisterServlet
com.xyx.register.persistence.dao.RegisterDao