widget/entry: Update show region geometry when entry is resized

widget/entry: Update show region geometry when entry is resized

It fixes the following problems.

 - elm_widget_show_region_set() could be called from
   inside of elm_widget_show_region_set(). And the last function call
   could be ignored and given values were abandoned.
   The patch updates show region values everytime.

 - When elm_entry is resized during processing elm_widget_show_region_set(),
   it must update its show region geometry to show proper region according to
   lastest geometry.
   The patch will show proper region of elm_entry's cursor.

@tizen_fix

Change-Id: Ia92a5232cfd26aa98075cdb9e4b54d376d1c44b7