[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: NBen Dooks <ben-linux@fluff.org>

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;
 }

arch/arm/mach-s3c2410/gpio.c

@@ -40,7 +40,7 @@ int s3c2410_gpio_irqfilter(unsigned int pin, unsigned int on,
 	unsigned long val;
 
 	if (pin < S3C2410_GPG(8) || pin > S3C2410_GPG(15))
-		return -1;
+		return -EINVAL;
 
 	config &= 0xff;
 

arch/arm/plat-s3c24xx/gpio.c

@@ -184,10 +184,10 @@ EXPORT_SYMBOL(s3c2410_modify_misccr);
 int s3c2410_gpio_getirq(unsigned int pin)
 {
 	if (pin < S3C2410_GPF(0) || pin > S3C2410_GPG(15))
-		return -1;	/* not valid interrupts */
+		return -EINVAL;	/* not valid interrupts */
 
 	if (pin < S3C2410_GPG(0) && pin > S3C2410_GPF(7))
-		return -1;	/* not valid pin */
+		return -EINVAL;	/* not valid pin */
 
 	if (pin < S3C2410_GPF(4))
 		return (pin - S3C2410_GPF(0)) + IRQ_EINT0;