chan_dahdi/sig_pri: Fix type mismatch in the idledial feature's channel creation.

Square pegs in round holes don't work very well.
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Merged revisions 418261 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 418262 from http://svn.asterisk.org/svn/asterisk/branches/11
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Merged revisions 418263 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@418264 65c4cc65-6c06-0410-ace0-fbb531ad65f3