remove redundant unless expression

Author: sfewer-r7

lib/msf/core/exploit/remote/http/cisco_ios_xe.rb

@@ -98,9 +98,7 @@ def run_os_command(cmd, admin_username, admin_password)
         'data' => json
       )
 
-      return false unless res&.code == 200
-
-      true
+      res&.code == 200
     end
   end
 end