dde_bsd: always advance play position

In addition to always sending the progress signal the driver
will also advance the play position, even if there is no valid
packet.

Issue genodelabs#1796.

repos/dde_bsd/src/drivers/audio/main.cc

@@ -141,11 +141,11 @@ class Audio_out::Out
 				p_left->mark_as_played();
 				p_right->mark_as_played();
 
-				_advance_position(p_left, p_right);
 			} else {
 				_play_silence();
 			}
 
+			_advance_position(p_left, p_right);
 
 			/* always report when a period has passed */
 			Session_component *channel_left  = channel_acquired[LEFT];