[dvsim/syn] Minor fix in message reporting

Signed-off-by: Michael Schaffner <msf@google.com>
diff --git a/util/dvsim/SynCfg.py b/util/dvsim/SynCfg.py
index 53473da..f408b79 100644
--- a/util/dvsim/SynCfg.py
+++ b/util/dvsim/SynCfg.py
@@ -364,7 +364,7 @@
             fail_msgs = ""
             for _, key in hdr_key_pairs:
                 if key in self.result['messages']:
-                    if self.result.get(key):
+                    if self.result['messages'].get(key):
                         self.errors_seen = True
                         break