ltq-adsl-mei: fix bugs in linux 3.18 compatiblity change

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

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@44845 3c298f89-4303-0410-b956-a3cf2f4a3e73