gpio: Use dev_fwnode() where applicable across drivers

gpio: Use dev_fwnode() where applicable across drivers

irq_domain_create_simple() takes fwnode as the first argument. It can be
extracted from the struct device using dev_fwnode() helper instead of
using of_node with of_fwnode_handle().

So use the dev_fwnode() helper where applicable.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20250611104348.192092-6-jirislaby@kernel.org
[Bartosz: tweaked the commit message]
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>