Fix the issue that App crash on startForeground.

Install single APP in any user space except Owner user, the APP
got crash when call startForeground in Service Component with
Notification which without SmallIcon.

bug:https://code.google.com/p/android/issues/detail?id=209043



Change-Id: I88a3b8afc213cafe0f280f9b44d6acd2ea0df207
Signed-off-by: Wang Le <wangle@xiaomi.com>