avsync-lib: refine video disc handling

Change-Id: I80b092058c93fcb5ac300a345ed0f96aee61c933
diff --git a/src/msync_util.h b/src/msync_util.h
index d9a1179..cb691d1 100644
--- a/src/msync_util.h
+++ b/src/msync_util.h
@@ -48,4 +48,5 @@
 int msync_session_set_audio_switch(int fd, bool start);
 int msync_session_get_clock_dev(int fd, int32_t *ppm);
 int msync_session_set_clock_dev(int fd, int32_t ppm);
+int msync_session_get_disc_thres(int session_id, uint32_t *min, uint32_t *max);
 #endif