catch exceptions as const

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ic8e6ade739bd5ea6e79cac6b9bb2b182748e10c8
diff --git a/extensions/openpower-pels/event_logger.hpp b/extensions/openpower-pels/event_logger.hpp
index d1736cc..eed2b81 100644
--- a/extensions/openpower-pels/event_logger.hpp
+++ b/extensions/openpower-pels/event_logger.hpp
@@ -140,7 +140,7 @@
             _creator(std::get<msgPos>(event), std::get<levelPos>(event),
                      std::get<adPos>(event).getData());
         }
-        catch (std::exception& e)
+        catch (const std::exception& e)
         {
             phosphor::logging::log<phosphor::logging::level::ERR>(
                 "EventLogger's create function threw an exception",