should decrease ec's ref_count when removing ec from post_updates
should decrease ec's ref_count when removing ec from post_updates

  because we increase ec's ref_count when adding ec to post_updates.

Change-Id: I44e47edfc031ba93ce0b67be9e5ad689db5fc97b

tizenorg/platform.upstream.enlightenment,tizenorg/platform.upstream.enlightenment,tizenorg/platform.upstream.enlightenment