[NAN] Change Broadcast for NAN status change to notification only

Remove information about current status of NAN. Receiver will have
to query that information explicitly. New pattern (per API council
review) - helps reduce window for having old information.

(cherry-pick of commit 905077a5)

Bug: 31470256
Test: unit tests & integration (sl4a) tests.
Change-Id: If3d0873989389e6c69feb0d02e5d0c79cdf9679e