vendor sepolicy: resolve a few denials

Change-Id: Icf55b522bbb5eae25c6a3e5e4bb7adb41f1790e2
diff --git a/sepolicy/private/update_engine.te b/sepolicy/private/update_engine.te
index d2ddcbe..89e89b6 100644
--- a/sepolicy/private/update_engine.te
+++ b/sepolicy/private/update_engine.te
@@ -19,3 +19,5 @@
 
 allow update_engine storage_file:lnk_file read;
 allow update_engine toolbox_exec:file { execute getattr };
+
+allow update_engine sepolicy_file:file { append };