Ensures that a single run of the interrupt service routine is consistent about whether there are VPMADT032 commands to process or not. Signed-off-by: Shaun Ruffell <sruffell@digium.com> git-svn-id: http://svn.asterisk.org/svn/dahdi/linux/trunk@9949 a0bf4364-ded3-4de4-8d8a-66a801d63aff