Change owner of ACPI BERT tables to system

Changes the owner of the following files to system:system:

* /sys/firmware/acpi/tables
* /sys/firmware/acpi/tables/BERT
* /sys/firmware/acpi/tables/data/BERT

This allows the bert_collector deamon to read these files for error reporting.

Bug: 357626966
Test: m && atest bert_collector_test

Change-Id: Iba3a169f1851566ee6fed6d41b538dae448bf811