ACPI: PMIC: constify all struct intel_pmic_opregion_data declarations

The struct intel_pmic_opregion_data declarations never change,
constify them all.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>