Add usbradio.conf.sample from branches/1.4/configs - r84162.

It was mistakenly deleted in 1.4 without ever being merged to trunk.

Reported by eliel on #asterisk-dev.


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@89132 65c4cc65-6c06-0410-ace0-fbb531ad65f3