audio: allow audio port cache update even when audio patches contain invalidated sources/sinks

When an audio device disconnects from Android, custom audio patches
containing the device become invalidated.
AudioManager::updateAudioPortCache() used to fail in that case, but
it causes onAudioPortListUpdated() event never gets called so that
the creator of the custom audio patch cannot update it. Let
updateAudioPortCached() succeed even in the case so that the entity
that created the audio patch can get notified.

Bug: 18909299
Change-Id: If4f6ed73f69213d792117fb42aec103ae2e50b79