platform/x86: x86-android-tablets: Stop using gpiolib private APIs

platform/x86: x86-android-tablets: Stop using gpiolib private APIs

Refactor x86_android_tablet_get_gpiod() to no longer use
gpiolib private functions like gpiochip_find().

As a bonus this allows specifying that the GPIO is active-low,
like the /CE (charge enable) pin on the bq25892 charger on
the Lenovo Yoga Tablet 3.

Reported-by: Bartosz Golaszewski <brgl@bgdev.pl>
Closes: https://lore.kernel.org/platform-driver-x86/20230905185309.131295-12-brgl@bgdev.pl/
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230909141816.58358-7-hdegoede@redhat.com