Add power stats HAL to ANR list

Bug: 135111122
Test: Ran "adb shell am hang" and verified that power.stats HAL
information is in /data/anr/<anr_file>
Change-Id: I60a6191626a20c737124033e8ad453fa91425e39
(cherry picked from commit 8273f1915f7a483770267cb8eeee55f994a4428c)
diff --git a/private/system_server.te b/private/system_server.te
index 20f2437..98dbdb5 100644
--- a/private/system_server.te
+++ b/private/system_server.te
@@ -284,6 +284,7 @@
   hal_graphics_composer_server
   hal_health_server
   hal_omx_server
+  hal_power_stats_server
   hal_sensors_server
   hal_vr_server
 }:process { signal };