ACPICA: Events: Fix an issue that _REG association can happen before namespace is initialized

ACPICA commit c508f8592efaa0d8197f26d7fee6382c5ac8e383

Current code flow cannot ensure _REG association can happen after the
namespace is initialized, so we move _REG association to where _REG was
about to run to fix this issue.

This issue is detected when acpi_ev_initialize_region() is invoked during
the table loading. And this is one of the most important the root cause why
ACPICA table loading is split into 2 load passes. Lv Zheng.

Link: https://github.com/acpica/acpica/commit/c508f859
Link: https://bugs.acpica.org/show_bug.cgi?id=1252


Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>