brcm47xx: add support for ipv6 in default network config

Modify /etc/init.d/netconfig to use UCI defaults for building the
default network config, which includes appropriate defaults for IPV6.

Signed-off-by: Nathan Hintz <nlhintz@hotmail.com>


git-svn-id: svn://svn.openwrt.org/openwrt/trunk@38294 3c298f89-4303-0410-b956-a3cf2f4a3e73