Sepolicy: Add theme service as system service

Change-Id: Idfb690be5d35c03610165b914c0a3f2260e68956
diff --git a/sepolicy/service_contexts b/sepolicy/service_contexts
index 09640f8..595d05e 100644
--- a/sepolicy/service_contexts
+++ b/sepolicy/service_contexts
@@ -1 +1,2 @@
 edgegestureservice                        u:object_r:system_server_service:s0
+themes                                    u:object_r:system_server_service:s0