BATestApp: Check adapter address before initializing BroadcastAddress

This change checks whether adapter address is properly initialized
or not before assigning it to BroadcastAddress in GattBroadcastService.
During user switch, it may happen that adapter address is not properly
initialized so assigning it to BroadcastAddress can make BATestApp
stop

Change-Id: I965126d097c17ac94e71bba1c218ed9953ddd562
CRs-Fixed: 2372179
1 file changed