android/hal-audio: Return proper latency for stream
android/hal-audio: Return proper latency for stream

This patch implements get_latency() for output stream properly by
returning some meaningful value, i.e. calculated duration of single
media packet increased by fixed A2DP playback latency. This is the
same as PulseAudio does.

pkarasev3/bluez,mapfau/bluez,ComputeCycles/bluez,ComputeCycles/bluez,mapfau/bluez,mapfau/bluez,silent-snowman/bluez,silent-snowman/bluez,pkarasev3/bluez,mapfau/bluez,pkarasev3/bluez,pkarasev3/bluez,pstglia/external-bluetooth-bluez,ComputeCycles/bluez,pstglia/external-bluetooth-bluez,silent-snowman/bluez,pstglia/external-bluetooth-bluez,ComputeCycles/bluez,silent-snowman/bluez,pstglia/external-bluetooth-bluez