Fix typo in confbridge.conf.sample

The denoise filter requires func_speex, not codec_speex.  Fix this in the
description of the denoise=yes option in confbridge.conf.
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Merged revisions 398820 from http://svn.asterisk.org/svn/asterisk/branches/11
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Merged revisions 398821 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: http://svn.asterisk.org/svn/asterisk/trunk@398822 f38db490-d61c-443f-a65b-d21fe96a405b