extend lock scope of vconf_lock in notify/ignore api

extend lock scope of vconf_lock in notify/ignore api

- Sometimes buxton client is closed by ohter thread,
  if vconf_lock is unlocked in notify/ignore API.
  There is no need to unlock vconf_lock before call buxton api,
  because noti_cb is called in idler.
  (noti callback which is called in wait_msg in buxton api causes dead lock)
  As a result, extend lock scope of vconf_lock.

Change-Id: Ib9883af231dc76c888d6b12334da70929169ddc0
Signed-off-by: Jiwoong Im <jiwoong.im@samsung.com>