Revert r370820

That change is wrong, wrong, wrong.

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@370821 65c4cc65-6c06-0410-ace0-fbb531ad65f3

contrib/realtime/mysql/voicemail_data.sql

@@ -23,9 +23,7 @@ CREATE TABLE voicemail_data (
 	-- Value of the channel variable VM_CATEGORY, if set
 	category CHAR(30),
 	-- Length of the message, in seconds
-	duration INT(11),
-	-- Unique identifier for the message
-	msg_id CHAR(32)
+	duration INT(11)
 );