gpio: rockchip: Do not mention legacy API in the code

Replace mentioning of legacy API by the latest one.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

drivers/gpio/gpio-rockchip.c

@@ -299,7 +299,7 @@ static int rockchip_gpio_set_config(struct gpio_chip *gc, unsigned int offset,
 }
 
 /*
- * gpiolib gpio_to_irq callback function. Creates a mapping between a GPIO pin
+ * gpiod_to_irq() callback function. Creates a mapping between a GPIO pin
  * and a virtual IRQ, if not already present.
  */
 static int rockchip_gpio_to_irq(struct gpio_chip *gc, unsigned int offset)