stream-manager-dbus: Improve ducking API regarding a stream not running

stream-manager-dbus: Improve ducking API regarding a stream not running

If there's only one stream that belongs to the target stream of ducking
effect and is not running, PA_CORE_HOOK_SINK_INPUT_RAMP_FINISH is not
invoked because it is not a stream to be rendered in this state.

This patch adds condition to use pa_sink_input_add_volume_factor() to
make the effect properly and to send the signal immediately in this case.

[Version] 11.1.70
[Issue Type] Bug fix

Change-Id: Id4339211318c8ce8388f2fce1b290b2a1dc1e09f
Signed-off-by: Sangchul Lee <sc11.lee@samsung.com>