Don't completely error out if a config file for chan_phone was not found....

Don't completely error out if a config file for chan_phone was not found. (issue #7710 reported by Mithraen)


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@39513 65c4cc65-6c06-0410-ace0-fbb531ad65f3