odhcp6c: allow setting a user-provided prefix as well

git-svn-id: svn://svn.openwrt.org/openwrt@35570 3c298f89-4303-0410-b956-a3cf2f4a3e73
kernel: update linux 3.7 to 3.7.7

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt@35571 3c298f89-4303-0410-b956-a3cf2f4a3e73