main: remove a stray second keyboard.init() call

Originally the keyboard was initialized in the user-session-specific
code, but it was later moved to the generic code. Except that it was
accidentally copied rather than moved.

https://bugzilla.gnome.org/show_bug.cgi?id=659940

js/ui/main.js

@@ -129,8 +129,6 @@ function _initRecorder() {
 function _initUserSession() {
     _initRecorder();
 
-    keyboard.init();
-
     global.screen.override_workspace_layout(Meta.ScreenCorner.TOPLEFT, false, -1, 1);
 
     ExtensionSystem.init();