broadcaster: Create notify after address getting

There could be a risk that before receiving advertising address a
request to get such address would be triggered. In such case it's
possible that empty (00:00:00:00:00:00) would be returned.
Create broadcast notification after getting advertising address would
limit this potential race call.

Tag: #bug
Bug: 335803667
Flag: EXEMPT: trivial fix - verified with unit tests and manual testing
Test: atest bluetooth_test_broadcaster
Change-Id: I9939fe64acb5e60d2334a783c8e6697f56bf0b9f