First I fixed the LuCI bug by running this command:
sed -i -e "s#depends('noresolv','')#depends('noresolv','0')#" /www/luci-static/resources/view/network/dhcp.js
Now when I try to change resolvfile name manually, over:
uci set dhcp.@dnsmasq.resolvfile="/etc/resolv.conf" /etc/init.d/dnsmasq restart
Then the resolvfile name is not changed in LuCI.
Can anyone help?