gpiolib: sanitize the return value of gpio_chip::get()

As per the API contract, the get() callback is only allowed to return 0,
1 or a negative error number. Add a wrapper around the callback calls
that filters out anything else.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20250210-gpio-sanitize-retvals-v1-4-12ea88506cb2@linaro.org


Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>