remove old depend on libfl for radvd menuconfig

git-svn-id: svn://svn.openwrt.org/openwrt/trunk/openwrt@633 3c298f89-4303-0410-b956-a3cf2f4a3e73

package/radvd/Config.in

 config BR2_PACKAGE_RADVD
 	select BR2_PACKAGE_KMOD_IPV6
-	select BR2_PACKAGE_LIBFL
 	tristate "radvd"
 	default m
 	help