Get rid of some inaccurate comments.

I'm doing some unrelated work in app_confbridge and finding
these "invalid pin" comments to be annoying. Get out!
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Merged revisions 402686 from http://svn.asterisk.org/svn/asterisk/branches/11
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Merged revisions 402687 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@402688 f38db490-d61c-443f-a65b-d21fe96a405b