audio policy: fix volume upon A2DP connection

audio policy: fix volume upon A2DP connection

setForceUse() should not force new device selection on outputs
if the selected device is 0. If a device 0 (no device) selection
is forced on a duplicated output, this causes volumes to be reset to
their default on outputs the duplicated output is connected to.

Also force reapply volumes when a new output is created. It is safer and more
explicit than relying on the fact that the selected volume is different
from default volume and thus is actually sent to audioflinger.

Bug 6658021.

Change-Id: I0a14d5229847e001b0d44f60d41c241efdb9946a