gpiolib: acpi: Extract acpi_request_own_gpiod() helper

It appears that we are using similar code excerpts for ACPI OpRegion
and event handling. Deduplicate those excerpts by extracting a new
acpi_request_own_gpiod() helper.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>