Fix advertising timeout behaviour.

When advertising is enabled with timeout, enable callback was not
called. Also we were not scheduling the disable operation after the
timeout passes. This patch fixes that. It also make sure that the
timeout callback is called on proper thread.

Bug: 34440704
Test: sl4a ConcurrentBleAdvertising:test_timeout
Change-Id: I233c2692c690f55ef6243325640e48b37818c9d5