Fix misspellings of "system", "controller", "interrupt" and "necessary".

Fix the various misspellings of "system", controller", "interrupt" and
"[un]necessary".

Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Signed-off-by: Adrian Bunk <bunk@kernel.org>
diff --git a/arch/arm/mach-at91/gpio.c b/arch/arm/mach-at91/gpio.c
index ba4a1bb..aa2d365 100644
--- a/arch/arm/mach-at91/gpio.c
+++ b/arch/arm/mach-at91/gpio.c
@@ -439,7 +439,7 @@
 		for (i = 0; i < 32; i++, pin++) {
 			/*
 			 * Can use the "simple" and not "edge" handler since it's
-			 * shorter, and the AIC handles interupts sanely.
+			 * shorter, and the AIC handles interrupts sanely.
 			 */
 			set_irq_chip(pin, &gpio_irqchip);
 			set_irq_handler(pin, handle_simple_irq);