Label persist audio properties

label all persist.audio.* properties
and allow mediaserver access to them.

Change-Id: If5755d9783dce298e66a25bcb7f17ff17bd83ea7
diff --git a/property.te b/property.te
index b62004e..ed84c64 100644
--- a/property.te
+++ b/property.te
@@ -7,3 +7,4 @@
 type ctl_default_prop, property_type;
 type ctl_dumpstate_prop, property_type;
 type ctl_rildaemon_prop, property_type;
+type audio_prop, property_type;