Add selinux contexts for system_config_service

Add selinux contexts for the new system config service.

Test: atest -it -w SystemConfigTest
Bug: 143112379
Change-Id: Ibe67acb404b6951e1fda9ce28bd50a0efdd44c5f
diff --git a/private/service_contexts b/private/service_contexts
index 26d9f5c..5a58ec8 100644
--- a/private/service_contexts
+++ b/private/service_contexts
@@ -201,6 +201,7 @@
 storagestats                              u:object_r:storagestats_service:s0
 SurfaceFlinger                            u:object_r:surfaceflinger_service:s0
 suspend_control                           u:object_r:system_suspend_control_service:s0
+system_config                             u:object_r:system_config_service:s0
 system_update                             u:object_r:system_update_service:s0
 task                                      u:object_r:task_service:s0
 telecom                                   u:object_r:telecom_service:s0