leds: trigger: gpio: Replace custom code for gpiod_get_optional()

leds: trigger: gpio: Replace custom code for gpiod_get_optional()

gpiod_get_optional() and currently used fwnode_gpiod_get_index()
are both wrappers against the same engine internally. Since we
have a pointer to struct device there is no reason to use fwnode
type of GPIO call. So, replace the current fwnode call by respective
gpiod ones.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20231103195310.948327-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Lee Jones <lee@kernel.org>