gpiolib: remove a redundant check in gpiod_to_chip()

This non-functional change slightly simplifies the implementation
of gpiod_to_chip() function.
Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpiolib.c

@@ -161,7 +161,7 @@ EXPORT_SYMBOL_GPL(desc_to_gpio);
  */
 struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc)
 {
-	if (!desc || !desc->gdev || !desc->gdev->chip)
+	if (!desc || !desc->gdev)
 		return NULL;
 	return desc->gdev->chip;
 }