ARM: S3C2410: Fix sparse warnings in arch/arm/mach-s3c2410/gpio.c

Fix sparse warning in arch/arm/mach-s3c2410/gpio.c due to missing
include of <mach/gpio-fns.h>. Fixes the following warning:

warning: symbol 's3c2410_gpio_irqfilter' was not declared. Should it be static?
Signed-off-by: Ben Dooks <ben-linux@fluff.org>

arch/arm/mach-s3c2410/gpio.c

@@ -28,6 +28,7 @@
 #include <linux/io.h>
 
 #include <mach/hardware.h>
+#include <mach/gpio-fns.h>
 #include <asm/irq.h>
 
 #include <mach/regs-gpio.h>