PCI: histb: Switch to using gpiod API

This patch switches the driver away from legacy gpio/of_gpio API to
gpiod API, and removes use of of_get_named_gpio_flags() which I want to
make private to gpiolib.

Link: https://lore.kernel.org/r/20220906204301.3736813-1-dmitry.torokhov@gmail.com


Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>