Move props out of exported3_system_prop

This is to remove bad context name "exported3_system_prop".

- persist.sys.device_provisioned -> provisioned_prop
- sys.retaildemo.enabled -> retaildemo_prop

Bug: 154885206
Test: boot device and see no denials
Change-Id: Ia19a19d93d0689deb56d66fe0b039ace44e4836f
diff --git a/private/system_server.te b/private/system_server.te
index a049696..bd87ead 100644
--- a/private/system_server.te
+++ b/private/system_server.te
@@ -620,6 +620,8 @@
 set_prop(system_server, audio_prop)
 set_prop(system_server, boot_status_prop)
 set_prop(system_server, surfaceflinger_color_prop)
+set_prop(system_server, provisioned_prop)
+set_prop(system_server, retaildemo_prop)
 userdebug_or_eng(`set_prop(system_server, wifi_log_prop)')
 
 # ctl interface