drivers: hwmon: (pmbus/ltc2978) Add support for LTM4686 uModule

This patch adds support for LTM4686 Ultrathin Dual 10A or
Single 20A uModule Regulator with Digital Power System Management.

Datasheet: http://www.analog.com/ltm4686

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
diff --git a/Documentation/hwmon/ltc2978 b/Documentation/hwmon/ltc2978
index 9a49d3c..dfb2caa 100644
--- a/Documentation/hwmon/ltc2978
+++ b/Documentation/hwmon/ltc2978
@@ -55,6 +55,10 @@
     Prefix: 'ltm4676'
     Addresses scanned: -
     Datasheet: http://www.linear.com/product/ltm4676
+  * Analog Devices LTM4686
+    Prefix: 'ltm4686'
+    Addresses scanned: -
+    Datasheet: http://www.analog.com/ltm4686
 
 Author: Guenter Roeck <linux@roeck-us.net>
 
@@ -76,6 +80,7 @@
 as two separate chips on two different I2C bus addresses.
 LTM4675 is a dual 9A or single 18A μModule regulator
 LTM4676 is a dual 13A or single 26A uModule regulator.
+LTM4686 is a dual 10A or single 20A uModule regulator.
 
 
 Usage Notes