devicestate.c: Minor tweaks

* In ast_state_chan2dev() use ARRAY_LEN() instead of a sentinel value in
chan2dev[].

* Fix some comments in chan_iax2.c.


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/13@422661 f38db490-d61c-443f-a65b-d21fe96a405b
Call IDs: Fix appearance of call ID in core show channels when NULL

NULL call IDs were meant to appear as '(none)' but instead were showing
the contents of an uninitialized character buffer.

ASTERISK-24223
Review: https://reviewboard.asterisk.org/r/3979/
........

Merged revisions 422664 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/13@422665 f38db490-d61c-443f-a65b-d21fe96a405b