Fix types in error-logging YAML to match openbmc standards

Change-Id: If5e2e534740f0675ba9294905ae531e015aed85a
Signed-off-by: Deepak Kodihalli <dkodihal@in.ibm.com>
diff --git a/tools/phosphor-logging/templates/elog-gen-template.mako.hpp b/tools/phosphor-logging/templates/elog-gen-template.mako.hpp
index b9d3d5e..5c11c1b 100644
--- a/tools/phosphor-logging/templates/elog-gen-template.mako.hpp
+++ b/tools/phosphor-logging/templates/elog-gen-template.mako.hpp
@@ -4,6 +4,7 @@
 // See elog-gen.py for more details
 #pragma once
 
+#include <string>
 #include <tuple>
 #include <type_traits>
 #include "log.hpp"