[ARM] 3342/1: NSLU2: Protect power button init routine with machine_is_nslu2()

Patch from Alessandro Zummo

The power button exit routine for the Linksys NSLU2 was not protected by
a machine_is_nslu2(). This patch fixes it.
Signed-off-by: NRod Whitby <rod@whitby.id.au>
Signed-off-by: NAlessandro Zummo <a.zummo@towertech.it>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mach-ixp4xx/nslu2-power.c

@@ -77,6 +77,9 @@ static int __init nslu2_power_init(void)
 
 static void __exit nslu2_power_exit(void)
 {
+	if (!(machine_is_nslu2()))
+		return;
+
 	free_irq(NSLU2_RB_IRQ, NULL);
 	free_irq(NSLU2_PB_IRQ, NULL);
 }