hwmon: (pmbus/adm1275) Add support for second current limit

ADM1275 supports a second current limit, which can be configured as either lower
or upper limit. Add support for it and report it as either lower or upper
critical current limit.

Also replace error return code EINVAL for unsupported pages with ENXIO as this
is more appropriate for the observed condition.

Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Acked-by: Jean Delvare <khali@linux-fr.org>
diff --git a/Documentation/hwmon/adm1275 b/Documentation/hwmon/adm1275
index 097b3cc..c438c98 100644
--- a/Documentation/hwmon/adm1275
+++ b/Documentation/hwmon/adm1275
@@ -60,5 +60,13 @@
 curr1_input		Measured current. From READ_IOUT register.
 curr1_max		Maximum current. From IOUT_OC_WARN_LIMIT register.
 curr1_max_alarm		Current high alarm. From IOUT_OC_WARN_LIMIT register.
+curr1_lcrit		Critical minimum current. Depending on the chip
+			configuration, either curr1_lcrit or curr1_crit is
+			supported, but not both.
+curr1_lcrit_alarm	Critical current low alarm.
+curr1_crit		Critical maximum current. Depending on the chip
+			configuration, either curr1_lcrit or curr1_crit is
+			supported, but not both.
+curr1_crit_alarm	Critical current high alarm.
 curr1_highest		Historical maximum current.
 curr1_reset_history	Write any value to reset history.