airmon-zc: minor variable fix

git-svn-id: http://svn.aircrack-ng.org/trunk@2405 28c6078b-6c39-48e3-add9-af49d547ecab
pull in PR7 from sh4rm4, wish I knew how to do this better but let this message show the true author: https://github.com/aircrack-ng/aircrack-ng/pull/7/

git-svn-id: http://svn.aircrack-ng.org/trunk@2406 28c6078b-6c39-48e3-add9-af49d547ecab
Merge branch 'master' into feature-ethers-file.