currently the keepalive option needs to be removed to fully disable it. this patch allows us to set it to 0. Signed-off-by: John Crispin <blogic@openwrt.org> git-svn-id: svn://svn.openwrt.org/openwrt/trunk@41438 3c298f89-4303-0410-b956-a3cf2f4a3e73