Add policy for __properties__ device.

Change-Id: Ie9b391283362fb6930f1ae858f0a879835c91e32
diff --git a/file_contexts b/file_contexts
index 7785f4e..26a1863 100644
--- a/file_contexts
+++ b/file_contexts
@@ -113,6 +113,7 @@
 /dev/watchdog		u:object_r:watchdog_device:s0
 /dev/xt_qtaguid	u:object_r:qtaguid_device:s0
 /dev/zero		u:object_r:zero_device:s0
+/dev/__properties__ u:object_r:properties_device:s0
 #############################
 # System files
 #