Remove duplicate allow rule.

"allow system apk_private_tmp_file:file relabelto" was already
added as part of 217f8afc
(https://android-review.googlesource.com/64890) and was added again
as part of commit 81ee5898. It
should not be here twice.

Change-Id: Ia7515f72ee6d9579ba52d72fcb0754733a2f6c27

system_server.te

@@ -42,7 +42,6 @@ allow system_server anr_data_file:dir relabelto;
 allow system_server system_data_file:dir relabelto;
 allow system_server apk_data_file:file relabelto;
 allow system_server apk_tmp_file:file relabelto;
-allow system_server apk_private_tmp_file:file relabelto;
 allow system_server cache_backup_file:file relabelto;
 allow system_server apk_private_tmp_file:file relabelto;
 allow system_server wallpaper_file:file relabelto;