ARM: 5768/1: ep93xx: remove dead code in ep93xx_gpio_ab_irq_handler()

Remove unnecessary code in ep93xx_gpio_ab_irq_handler().

The desc calculation for gpio port B was left in when the following
commit was merged.

commit d8aa0251
Author: Dmitry Baryshkov <dbaryshkov@gmail.com>
Date:   Thu Oct 9 13:36:24 2008 +0100

    [ARM] 5298/1: Drop desc_handle_irq()

It's not needed so remove it.
Signed-off-by: NH Hartley Sweeten <hsweeten@visionengravers.com>
Acked-by: NRyan Mallon <ryan@bluewatersys.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mach-ep93xx/core.c

@@ -206,7 +206,6 @@ static void ep93xx_gpio_ab_irq_handler(unsigned int irq, struct irq_desc *desc)
 	for (i = 0; i < 8; i++) {
 		if (status & (1 << i)) {
 			int gpio_irq = gpio_to_irq(EP93XX_GPIO_LINE_B(0)) + i;
-			desc = irq_desc + gpio_irq;
 			generic_handle_irq(gpio_irq);
 		}
 	}