Removed non-phpdoc @internal tags

Removed 2 @internal phpdoc tags as they were about old internal api usage and these methods are public api as @beberlei & @Ocramius confirmed on irc #doctrine

> ocramius: the @internal are old comments that were used to tell information about internal API usage
> ocramius: they are not the @internal of phpdoc, so you are welcome to send a PR to fix that