xtables-addons: fix missing conversion from r38021 (resolves a broken dependency)

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@38124 3c298f89-4303-0410-b956-a3cf2f4a3e73