Cleanup chan_local.c:local_new().

* Remove t and ama local variables.  There is no way they could be
anything other than default because p->owner can only be NULL at this
point.

* Rename tmp and tmp2 to owner and chan respectively.

* Remove redundant initialization of channel context, exten, priority.


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@387260 65c4cc65-6c06-0410-ace0-fbb531ad65f3