gpiolib: of: add quirk for locating reset lines with legacy bindings

Some legacy mappings used "gpio[s]-reset" instead of "reset-gpios",
add a quirk so that gpiod API will still work on unmodified DTSes.

Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>