Dnssec is never enabled on recent master

[Sami Olmari]

This commit https://github.com/openwrt/openwrt/commit/064dc1e81bc85f6ef8becc38854292853a59d2c2
breaks all dnssec, it will never get enabled despite /etc/config/dhcp
enabling it. Reverting this commit made dnssec to work again. So this
needs either reverting, or some more elaborate fix.

Additionally I got this message when troubleshooting this at irc:
"While at it, ask please to fix trust-anchor match too (it's not an
option, the option just contains that word at the end)"

Thank you!

-- 
 Sami Olmari
 Oy Olmari Ab
 Vaasa Hacklab ry