gpio: 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.

Preparatory patch for the removal of the 'irq' argument from irq flow
handlers.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Cc: Alexandre Courbot <gnurou@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c
index ab660e4..b65d2b8 100644
--- a/drivers/gpio/gpio-mvebu.c
+++ b/drivers/gpio/gpio-mvebu.c
@@ -460,7 +460,7 @@
 
 static void mvebu_gpio_irq_handler(unsigned int irq, struct irq_desc *desc)
 {
-	struct mvebu_gpio_chip *mvchip = irq_get_handler_data(irq);
+	struct mvebu_gpio_chip *mvchip = irq_desc_get_handler_data(desc);
 	struct irq_chip *chip = irq_desc_get_chip(desc);
 	u32 cause, type;
 	int i;