[dvsim/lint] Minor fixes for printout issues and result parser status

This adds a missing \n before the triple back-ticks around the tool
messages. Also, the position of the messages is corrected, and the
return value of the lint parser scripts is fixed.

Signed-off-by: Michael Schaffner <msf@google.com>
diff --git a/util/dvsim/utils.py b/util/dvsim/utils.py
index fc9df52..769a265 100644
--- a/util/dvsim/utils.py
+++ b/util/dvsim/utils.py
@@ -366,7 +366,7 @@
     '''
     md_results = ""
     if msg_list:
-        md_results += msg_list_title
+        md_results += msg_list_title + "\n"
         md_results += "```\n"
         for k, msg in enumerate(msg_list):
             if k <= max_msg_count or max_msg_count < 0: