efl_ui_tab_pager: remove the setter for tab_bar
the setter of the tab_bar here is quite useless. If you set it after
something else was set, the item situation is not clear anymore, there
is more in the spotlight than in the bar. You cannot use the widget
without tab bar. So the logical consequence for me was that the pager
create the tab bar by itself, and you can just access it via a getter.
Reviewed-by: WooHyun Jung <email@example.com>
Differential Revision: https://phab.enlightenment.org/D9731