Fix core dump on CLI usage

Fix issue with 'unistim show info' CLI command when device connected not configured
........

Merged revisions 382827 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@382828 65c4cc65-6c06-0410-ace0-fbb531ad65f3