AudioPolicy: managerdefault: fix onAudioDeviceUpdate callback

Scenario: startAudioSource (SW bridge) started, then stopped.
AF patch is released, so PlaybackThread has empty patch.

Next playback using the same sink will not recreate any patch
on AF as same device (and output desc has still valid patch handle)

Hence, ioconfichanged will get PORT NONE as sink device, no
onAudioDeviceUpdate cb can be fired.

This CL fixes this issue by reset of patch handle on the output

Bug: 136121584
Test: startAudioSource / stopAudioSource then playback on the same
sink. Ensure onAudioDeviceUpdate is fired
Test: atest RoutingTest

Signed-off-by: Francois Gaffie <francois.gaffie@renault.com>
Change-Id: Ia9c2570f687166f38335ed7efae28920f7acc474