elm_widget_item_static_focus: fix ERR prints

elm_widget_item_static_focus: fix ERR prints

There is the case that the deletion of the adapter can cause another
registeration, which then calls another time prepare, which then deletes
the adapter, before the actaul deletion of the first efl_del happened,
which means it will throw an error. To avoid this we track if we are in
process of a unrealization, and if so, do not delete the item there.

Reviewed-by: YeongJong Lee <yj34.lee@samsung.com>
Differential Revision: https://phab.enlightenment.org/D7453