Some older Asttribanks had an empty label string. They should be ignored when testing for a duplicate label at device probe time. While we're at it, reduce panic level in the notice. Signed-off-by: Tzafrir Cohen <tzafrir.cohen@xorcom.com> git-svn-id: http://svn.asterisk.org/svn/dahdi/linux/trunk@9925 a0bf4364-ded3-4de4-8d8a-66a801d63aff