ARM: SAMSUNG: Documentation: add documentation on GPIO code

Add some documentation in Documentation/arm/Samsung for the GPIO code
and where to look for the necessary functions. Update the S3C24XX case
as well.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
diff --git a/Documentation/arm/Samsung-S3C24XX/GPIO.txt b/Documentation/arm/Samsung-S3C24XX/GPIO.txt
index 228ecb6..816d607 100644
--- a/Documentation/arm/Samsung-S3C24XX/GPIO.txt
+++ b/Documentation/arm/Samsung-S3C24XX/GPIO.txt
@@ -12,6 +12,8 @@
   of the s3c2410 GPIO system, please read the Samsung provided
   data-sheet/users manual to find out the complete list.
 
+  See Documentation/arm/Samsung/GPIO.txt for the core implemetation.
+
 
 GPIOLIB
 -------