lavd/pulse_audio_enc: fix flush return code

Successful flushing is reported by returning 1 instead of 0.
Signed-off-by: Lukasz Marek <lukasz.m.luki@gmail.com>

libavdevice/pulse_audio_enc.c

@@ -102,7 +102,7 @@ static int pulse_write_packet(AVFormatContext *h, AVPacket *pkt)
             av_log(s, AV_LOG_ERROR, "pa_simple_flush failed: %s\n", pa_strerror(error));
             return AVERROR(EIO);
         }
-        return 0;
+        return 1;
     }
 
     if (pkt->dts != AV_NOPTS_VALUE)