What @luckydeveloper answered is a solution but it is better you upgrade your solutions to SP2013 version aswell. You must make the package product version to 15.0.
You are getting the error because your user controls .cs file has a CONTROLTEMPLATES which you have to convert to CONTROLTEMPLATES/15/. Check my thread on
How to upgrade a SharePoint 2010 Project to SharePoint 2013 (WebParts, MasterPage, App Page, User Controls) in Visual Studio 2012How to upgrade a SharePoint 2010 Project to SharePoint 2013 (WebParts, MasterPage, App Page, User Controls) in Visual Studio 2012 -Point 6
