gpio: swnode: don't use the swnode's name as the key for GPIO lookup

gpio: swnode: don't use the swnode's name as the key for GPIO lookup

Looking up a GPIO controller by label that is the name of the software
node is wonky at best - the GPIO controller driver is free to set
a different label than the name of its firmware node. We're already being
passed a firmware node handle attached to the GPIO device to
swnode_get_gpio_device() so use it instead for a more precise lookup.

Acked-by: Linus Walleij <linus.walleij@linaro.org>
Fixes: e7f9ff5dc90c ("gpiolib: add support for software nodes")
Link: https://lore.kernel.org/r/20251103-reset-gpios-swnodes-v4-4-6461800b6775@linaro.org
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>