frameworks/base lights: Always allow LineageNotificationLights set the default color

*) Oreo sdk onwards deprecates notification DEFAULT_LIGHTS.  However,
   LineageNotificationLights currently uses this flag to determine
   if we should generate an app specific color.

*) Use a light color of 0 to indicate that the app (or channel) has not
   set an explicit preference and that lineage lights should set a
   default.

Change-Id: I1f655aa17cb97c5a042a424ad1e8bd9d5ddec9a2