genlist: remove annoying error message

genlist: remove annoying error message

Summary:
content couldn't be always a elm widget.
After checking whether it's elm widget or not, use widget API

Test Plan:
terminology -> options -> font -> select font and check below error message

ERR<25935>:eo lib/eo/eo.c:603 _eo_call_resolve() in elm_widget.eo.c:8: you called func 'elm_obj_widget_focus_get' (213) which is unknown in class 'Edje_Object'.

Reviewers: raster, cedric, seoz, Hermet

Reviewed By: Hermet

Subscribers: seoz

Differential Revision: https://phab.enlightenment.org/D1186