ACPI / PMIC: Do not register handlers for unhandled OpRegions

For some model PMIC's used on Intel boards we do not know how to
handle the power or thermal opregions because we have no documentation.

For example in the intel_pmic_chtwc.c driver thermal_table_count is 0,
which means that our PMIC_THERMAL_OPREGION_ID handler will always fail
with AE_BAD_PARAMETER, in this case it is better to simply not register
the handler at all.

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