ACPI / PMIC: xpower: Add support for the GPI1 regulator to the OpRegion handler

Some Bay Trail devices use a GPI1 regulator field (address 0x4c) in
their 0x8d power OpRegion, add support for this.

This fixes AE_BAD_PARAMETER errors getting thrown on these devices and
fixes these errors causing these devices to not suspend.

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>