gpiolib: acpi: Don't use GPIO chip fwnode in acpi_gpiochip_find()

GPIO library should rely only on the GPIO device's fwnode.
Hence, replace GPIO chip fwnode usage by respective handle
of the GPIO device.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Benjamin Tissoires <bentiss@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>