autoservice: fix reference leak of logger callid.

autoservice acquires a local reference to the logger callid of each channel
in a loop.  This local reference was not released, causing the callid of
every channel in autoservice to leak.  This change moves the callid unref
inside the loop.

ASTERISK-23616 #close
Reported by: ibercom


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/11@412305 65c4cc65-6c06-0410-ace0-fbb531ad65f3