hwmon: (max34440) Add support for 'lowest' output voltage attribute

MAX34440 and compatibles support reporting the lowest measured output voltage.
Add support for it.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Jean Delvare <khali@linux-fr.org>
diff --git a/Documentation/hwmon/max34440 b/Documentation/hwmon/max34440
index 8ab5153..36b335c 100644
--- a/Documentation/hwmon/max34440
+++ b/Documentation/hwmon/max34440
@@ -56,6 +56,7 @@
 in[1-6]_max_alarm	Voltage high alarm. From VOLTAGE_OV_WARNING status.
 in[1-6]_lcrit_alarm	Voltage critical low alarm. From VOLTAGE_UV_FAULT status.
 in[1-6]_crit_alarm	Voltage critical high alarm. From VOLTAGE_OV_FAULT status.
+in[1-6]_lowest		Historical minimum voltage.
 in[1-6]_highest		Historical maximum voltage.
 in[1-6]_reset_history	Write any value to reset history.