mt76 - fix build error
mt76 was in Turris repo, but nowdays it isn't included.
According to @mhrusecky it doesn't build.
More details here:
https://forum.turris.cz/t/3-8-3-in-rc-dnsmasq-security-fixes-and-more/5290/7?u=pepe
https://forum.turris.cz/t/3-8-3-in-rc-dnsmasq-security-fixes-and-more/5290/10?u=pepe