hwmon: Define sysfs interface for energy consumption register

Describe the sysfs files that were introduced in the ibmaem driver.
Signed-off-by: NDarrick J. Wong <djwong@us.ibm.com>
Signed-off-by: NJean Delvare <khali@linux-fr.org>

Documentation/hwmon/sysfs-interface

@@ -329,6 +329,10 @@ power[1-*]_average		Average power use
 				Unit: microWatt
 				RO
 
+power[1-*]_average_interval	Power use averaging interval
+				Unit: milliseconds
+				RW
+
 power[1-*]_average_highest	Historical average maximum power use
 				Unit: microWatt
 				RO
@@ -353,6 +357,14 @@ power[1-*]_reset_history	Reset input_highest, input_lowest,
 				average_highest and average_lowest.
 				WO
 
+**********
+* Energy *
+**********
+
+energy[1-*]_input		Cumulative energy use
+				Unit: microJoule
+				RO
+
 **********
 * Alarms *
 **********