comment on ipaccess-find: Work without providing an interface name

Hi Holger, I think this patch is wrong: http://cgit.osmocom.org/cgit/openbsc/commit/?id=d3080be1317cfa0269b1c12c8f28... ifname should be set if argc == 2, but it seems to be set if argc < 2, in that case argv[1] is always NULL.