libaudioclient: force onAudioDeviceUpdate on registration

This CL forces the onAudioDeviceUpdate on register event.
It also fixes the loss of callback on AudioTrack or AudioRecord
client if received before ioHandle is assigned.

Test: audio smoke tests
Test: CTS for AudioTrack and AudioRouting

Change-Id: I119b5c407da68a5b55162550bea5fa7e724165d1
Signed-off-by: Francois Gaffie <francois.gaffie@renault.com>