catch exceptions as const

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ic8e6ade739bd5ea6e79cac6b9bb2b182748e10c8
diff --git a/extensions/openpower-pels/failing_mtms.cpp b/extensions/openpower-pels/failing_mtms.cpp
index 386f496..0e82bd0 100644
--- a/extensions/openpower-pels/failing_mtms.cpp
+++ b/extensions/openpower-pels/failing_mtms.cpp
@@ -49,7 +49,7 @@
         unflatten(pel);
         validate();
     }
-    catch (std::exception& e)
+    catch (const std::exception& e)
     {
         log<level::ERR>("Cannot unflatten failing MTM section",
                         entry("ERROR=%s", e.what()));