[dvsim] Fix publish report summary typo

This PR fixes a publish report error that causes the nightly regression
summary report to be empty.

Signed-off-by: Cindy Chen <chencindy@opentitan.org>
diff --git a/util/dvsim/FlowCfg.py b/util/dvsim/FlowCfg.py
index e25a705..fd64b0e 100644
--- a/util/dvsim/FlowCfg.py
+++ b/util/dvsim/FlowCfg.py
@@ -411,7 +411,7 @@
 
         if self.is_primary_cfg:
             self.gen_results_summary()
-            self.write_results_html("summary.html", item.results_summary_md)
+            self.write_results_html("summary.html", self.results_summary_md)
         self.gen_email_html_summary()
 
     def gen_results_summary(self):