Be specific about the type of hash

See rapid7#2583. Since there are several types of hashes, we need to be more
specific about this -- see modules/exploits/windows/smb/psexec.rb which
uses an "smb_hash" as a password type.

Also, the fixes in rapid7#2583 do not appear to address anything else reported
on the Redmine issue, namely, operating system and architecture
identification discovered with this module (assuming good credentials).
Therefore, the Redmine issue should not be considered resolved.

[SeeRM rapid7#4398]

Author: Tod Beardsley

modules/auxiliary/admin/mysql/mysql_enum.rb

@@ -91,7 +91,7 @@ def run
           :port  => rport,
           :user  => row[0],
           :pass  => row[2],
-          :type  => "hash",
+          :type  => "mysql_hash",
           :sname => "mysql",
           :active => true
         })