Don't use MESSAGE in elog metadata

That name is already used by the journal, and strange things
can happen when there are two MESSAGE fields in a single journal
entry. For example, dumping the journal without the verbose option
will show that metadata as a standalone journal entry.

Change-Id: Ibc45799063f7b50b2f39a068192333bf57244d52
Signed-off-by: Matt Spinler <spinler@us.ibm.com>
diff --git a/power-supply/power_supply.cpp b/power-supply/power_supply.cpp
index 3626cb3..f8c86e3 100644
--- a/power-supply/power_supply.cpp
+++ b/power-supply/power_supply.cpp
@@ -626,7 +626,7 @@
     {
         log<level::INFO>("Failed to resolve error",
                          entry("CALLOUT=%s", callout.c_str()),
-                         entry("MESSAGE=%s", message.c_str()));
+                         entry("ERROR=%s", message.c_str()));
     }
 
 }