gpio: Congatec Board Controller gpio driver

Add gpio support for the Congatec Board Controller.
This Board Controller has 14 GPIO pins.

The driver is probed by the Congatec Board Controller MFD driver.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Thomas Richard <thomas.richard@bootlin.com>
Acked-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Link: https://lore.kernel.org/r/20241001-congatec-board-controller-v3-2-39ceceed5c47@bootlin.com


Signed-off-by: Lee Jones <lee@kernel.org>