Keyboard: Refactor Levinson to use split common code (#3639)

* Migrate Levinson to use split_common code

* Update keymap

keyboards/levinson/config.h

@@ -1,6 +1,7 @@
 /*
 Copyright 2012 Jun Wako <wakojun@gmail.com>
 Copyright 2015 Jack Humbert
+Copyright 2018 Danny Nguyen <danny@keeb.io>
 
 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
@@ -21,11 +22,4 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #include "config_common.h"
 
-#ifdef SUBPROJECT_rev1
-    #include "rev1/config.h"
-#endif
-#ifdef SUBPROJECT_rev2
-    #include "rev2/config.h"
-#endif
-
 #endif