riff: add siren to the RIFF parser

Add siren7 caps to the RIFF parser.
diff --git a/gst-libs/gst/riff/riff-ids.h b/gst-libs/gst/riff/riff-ids.h
index 81b7626..b9526d6 100644
--- a/gst-libs/gst/riff/riff-ids.h
+++ b/gst-libs/gst/riff/riff-ids.h
@@ -407,6 +407,7 @@
 #define GST_RIFF_WAVE_FORMAT_IPI_RPELP      (0x0251)
 #define GST_RIFF_WAVE_FORMAT_CS2            (0x0260)
 #define GST_RIFF_WAVE_FORMAT_SONY_ATRAC3    (0x0270)
+#define GST_RIFF_WAVE_FORMAT_SIREN          (0x028E)
 #define GST_RIFF_WAVE_FORMAT_FM_TOWNS_SND   (0x0300)
 #define GST_RIFF_WAVE_FORMAT_BTV_DIGITAL    (0x0400)
 #define GST_RIFF_WAVE_FORMAT_IMC            (0x0401)