If you want to investigate the problem, you need to post the result of the following commands:
head -n -0 -v /etc/resolv* /tmp/resolv* /tmp/resolv*/*
Otherwise two workarounds should be possible:
uci set network.wan.peerdns="0"
uci add_list network.wan.dns="8.8.8.8"
uci add_list network.wan.dns="8.8.4.4"
uci commit network
/etc/init.d/network restart
or
uci add_list dhcp.@dnsmasq[0].server="8.8.8.8"
uci add_list dhcp.@dnsmasq[0].server="8.8.4.4"
uci commit dhcp
/etc/init.d/dnsmasq restart