Add rule for new system service

- Update policy for new system service, used for AiAi/Apps to
  present data in their UI.

Bug: 173243538
Bug: 176208267
Test: manual. Can boot to home and get manager successfully.
Change-Id: Ie88c6fa7ed80c0d695daaa7a9c92e11ce0fed229
diff --git a/private/service_contexts b/private/service_contexts
index b13f163..756fa1d 100644
--- a/private/service_contexts
+++ b/private/service_contexts
@@ -243,6 +243,7 @@
 time_zone_detector                        u:object_r:timezonedetector_service:s0
 timezone                                  u:object_r:timezone_service:s0
 thermalservice                            u:object_r:thermal_service:s0
+transformer                               u:object_r:transformer_service:s0
 trust                                     u:object_r:trust_service:s0
 tv_input                                  u:object_r:tv_input_service:s0
 tv_tuner_resource_mgr                     u:object_r:tv_tuner_resource_mgr_service:s0