Fix callback unit test failure

Recently changes has been done in phosphor-logging commit
method causing the unit test failure with error message
"Error in mapper call". Earlier commit method
used to return error but the same has been modified to throw
exception now.

Fixed to return from the callback method if context is
start

Change-Id: I606c638bd2d0bc2003af0b284586e53809bbca21
Signed-off-by: Marri Devender Rao <devenrao@in.ibm.com>
diff --git a/src/elog.hpp b/src/elog.hpp
index 996fd58..24e2009 100644
--- a/src/elog.hpp
+++ b/src/elog.hpp
@@ -154,6 +154,12 @@
      */
     void operator()(Context ctx) override
     {
+        if (ctx == Context::START)
+        {
+            // No action should be taken as this call back is being called from
+            // daemon Startup.
+            return;
+        }
         auto data = captureMetadata();
 
         phosphor::logging::report<errorType>(metadataType(data.c_str()));