PEL: Add UPS informational errors

Add informational errors to the message registry for the following
Uninterruptible Power Supply (UPS) events:
* Battery is discharging due to a utility failure
* Battery level is low

The Name property of the new entries was designed to match the
terminology used in the UPower Device D-Bus interface.  This interface
is used to publish the current UPS status.  For more information see
https://upower.freedesktop.org/docs/Device.html

Tested:
* Manually logged the following errors using busctl:
  * xyz.openbmc_project.Power.UPS.Error.Battery.Discharging
  * xyz.openbmc_project.Power.UPS.Error.Battery.Low
* Verified all field values in the resulting error logs

Signed-off-by: Shawn McCarney <shawnmm@us.ibm.com>
Change-Id: I98a3451d9d2c5f906ddf919e9bb2a99500907b80
diff --git a/extensions/openpower-pels/registry/message_registry.json b/extensions/openpower-pels/registry/message_registry.json
index 1acfb25..5e3e707 100644
--- a/extensions/openpower-pels/registry/message_registry.json
+++ b/extensions/openpower-pels/registry/message_registry.json
@@ -1889,6 +1889,48 @@
         },
 
         {
+            "Name": "xyz.openbmc_project.Power.UPS.Error.Battery.Discharging",
+            "Subsystem": "power",
+            "Severity": "non_error",
+            "ActionFlags": ["report"],
+            "ComponentID": "0x2700",
+
+            "SRC": {
+                "Type": "11",
+                "ReasonCode": "0x4201",
+                "Words6To9": {}
+            },
+
+            "Documentation": {
+                "Description": "The Uninterruptible Power Supply (UPS) battery is discharging and providing power to the system due to a utility failure",
+                "Message": "The Uninterruptible Power Supply (UPS) battery is discharging and providing power to the system due to a utility failure",
+                "Notes": [
+                ]
+            }
+        },
+
+        {
+            "Name": "xyz.openbmc_project.Power.UPS.Error.Battery.Low",
+            "Subsystem": "power",
+            "Severity": "non_error",
+            "ActionFlags": ["report"],
+            "ComponentID": "0x2700",
+
+            "SRC": {
+                "Type": "11",
+                "ReasonCode": "0x4203",
+                "Words6To9": {}
+            },
+
+            "Documentation": {
+                "Description": "The Uninterruptible Power Supply (UPS) battery level is low",
+                "Message": "The Uninterruptible Power Supply (UPS) battery level is low",
+                "Notes": [
+                ]
+            }
+        },
+
+        {
             "Name": "xyz.openbmc_project.Power.Regulators.Error.ConfigFile",
             "Subsystem": "power",
             "ComponentID": "0x2700",