ACPICA: Events: Split acpi_ev_associate_reg_method() from region initialization code

ACPICA commit 87c85610250ff7141a84507f68dbc1e00f2936db

This patch introduces a new region initialization function
acpi_ev_associate_reg_method(), which is invoked to associate the _REG method
to its related region object.

Region object's default value assignments are also sorted by cleaning up
the code using this new function. Lv Zheng.

Link: https://github.com/acpica/acpica/commit/87c85610
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>

drivers/acpi/acpica/acevents.h

@@ -198,6 +198,8 @@ void
 acpi_ev_detach_region(union acpi_operand_object *region_obj,
 		      u8 acpi_ns_is_locked);
 
+void acpi_ev_associate_reg_method(union acpi_operand_object *region_obj);
+
 acpi_status
 acpi_ev_execute_reg_methods(struct acpi_namespace_node *node,
 			    acpi_adr_space_type space_id);