elm_clock: fix theme apply
elm_clock: fix theme apply

Summary:
theme change was delayed untill some other change (i.e. mode change, clock update)
@fix

Test Plan:
1. create new style "test" for elm_clock
2. add this style to theme
3. compare results of following modifications of src/examples/clock_example.c:

```
   /* am/pm */
   ck = elm_clock_add(win);
   elm_object_style_set(ck, "test"); //style is applied before ap_pm set
   elm_clock_show_am_pm_set(ck, EINA_TRUE);
```
and
```
   /* am/pm */
   ck = elm_clock_add(win);
   elm_clock_show_am_pm_set(ck, EINA_TRUE);
   elm_object_style_set(ck, "test"); //style is applied after ap_pm set
```
ExR: style is applied in both cases
Result without this patch: style is applied only in first case

Reviewers: cedric, seoz, raster, reutskiy.v.v, Hermet

Reviewed By: Hermet

Differential Revision: https://phab.enlightenment.org/D2349

rvandegrift/elementary,rvandegrift/elementary,FlorentRevest/Elementary,tasn/elementary,rvandegrift/elementary,FlorentRevest/Elementary,tasn/elementary,rvandegrift/elementary,FlorentRevest/Elementary,FlorentRevest/Elementary,tasn/elementary,tasn/elementary,tasn/elementary