pinctrl: Use irq_desc_get_xxx() to avoid redundant lookup of irq_desc

Use irq_desc_get_xxx() to avoid redundant lookup of irq_desc while we
already have a pointer to corresponding irq_desc.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: linux-gpio@vger.kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

drivers/pinctrl/pinctrl-at91.c

@@ -1596,7 +1596,7 @@ static struct irq_chip gpio_irqchip = {
 
 static void gpio_irq_handler(unsigned irq, struct irq_desc *desc)
 {
-	struct irq_chip *chip = irq_get_chip(irq);
+	struct irq_chip *chip = irq_desc_get_chip(desc);
 	struct gpio_chip *gpio_chip = irq_desc_get_handler_data(desc);
 	struct at91_gpio_chip *at91_gpio = container_of(gpio_chip,
 					   struct at91_gpio_chip, chip);