[ARM] S3C24XX: GPIO: Fix error returns from gpio functions

Several GPIO functions have been returning -1 to indicate
an error instead of returning a proper error code. Change
to return -EINVAL for invalid argument(s).

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
diff --git a/arch/arm/mach-s3c2400/gpio.c b/arch/arm/mach-s3c2400/gpio.c
index 81ebe2f..6c68e78 100644
--- a/arch/arm/mach-s3c2400/gpio.c
+++ b/arch/arm/mach-s3c2400/gpio.c
@@ -33,8 +33,8 @@
 
 int s3c2400_gpio_getirq(unsigned int pin)
 {
-	if (pin < S3C2410_GPE(0) || pin > S3C2400_GPE7_EINT7)
-		return -1;  /* not valid interrupts */
+	if (pin < S3C2410_GPE(0) || pin > S3C2400_GPE(7))
+		return -EINVAL;  /* not valid interrupts */
 
 	return (pin - S3C2410_GPE(0)) + IRQ_EINT0;
 }