ACPICA: Add __init for ACPICA initializers/finalizers.

This patch adds __init to the ACPICA documented initializers:
  acpi_initialize_tables()
  acpi_initialize_subsystem()
  acpi_load_tables()
  acpi_enable_subsystem()
  acpi_initialize_objects()
and to acpi_reallocate_root_table(), acpi_find_root_pointer() which
are also meant to be called only during initialization.

This patch adds __init to the ACPICA documented finalizer:
  acpi_terminate()
as this finalizer is only called in __init function now.

This change helps to reduce source code differences between
ACPICA upstream and Linux.

[rjw: Changelog]
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>