Return CheckCode::Unsupported in ETERNALBLUE

Defining a check method in the module overrides it.

modules/exploits/windows/smb/ms17_010_eternalblue.rb

@@ -108,6 +108,7 @@ class MetasploitModule < Msf::Exploit::Remote
 
   def check
     # todo: create MS17-010 mixin, and hook up auxiliary/scanner/smb/smb_ms17_010
+    CheckCode::Unsupported
   end
 
   def exploit