Fix a bug where a value used to create the channel name was bogus.

Fix a bug where a value used to create the channel name was bogus.

This commit fixes the scenario where an incoming call is authenticated
using a peer entry. Previously the channel name was created using either
the username setting from the sip.conf entry or the IP address that the
call came from. Now the channel name will be created using the peer name
itself. This commit will not change the way the channel name is generated
for users or friends.

(closes issue #14256)
Reported by: Nick_Lewis
Patches:
      chan_sip.c-chname.patch uploaded by Nick (license 657)
Tested by: Nick_Lewis, file

git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.4@188946 65c4cc65-6c06-0410-ace0-fbb531ad65f3