i2c-piix4: Add support for the ATI SB600

Add support for the ATI SB600 SMBus controller.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
diff --git a/Documentation/i2c/busses/i2c-piix4 b/Documentation/i2c/busses/i2c-piix4
index 9214763..7cbe43f 100644
--- a/Documentation/i2c/busses/i2c-piix4
+++ b/Documentation/i2c/busses/i2c-piix4
@@ -6,7 +6,7 @@
     Datasheet: Publicly available at the Intel website
   * ServerWorks OSB4, CSB5, CSB6 and HT-1000 southbridges
     Datasheet: Only available via NDA from ServerWorks
-  * ATI IXP southbridges IXP200, IXP300, IXP400
+  * ATI IXP200, IXP300, IXP400 and SB600 southbridges
     Datasheet: Not publicly available
   * Standard Microsystems (SMSC) SLC90E66 (Victory66) southbridge
     Datasheet: Publicly available at the SMSC website http://www.smsc.com