elm_gen****: fix focus restoring on window focus changes

elm_gen****: fix focus restoring on window focus changes

this ensures that if there is no focused item, that at least the
container is focused. This leads to the fact that the elm_genlist
/elm_gengrid is refocused when a window is unfocused and focused again.

Reviewed-by: YeongJong Lee <yj34.lee@samsung.com>
Differential Revision: https://phab.enlightenment.org/D7451