dnsmasq: make bind-dynamic 'non-wildcard' interfaces default

dnsmasq: make bind-dynamic 'non-wildcard' interfaces default

'non-wildcard' interfaces enables dnsmasq's '--bind-dynamic' mode.  This
binds to interfaces rather than wildcard addresses *and* keeps track of
interface comings/goings via a unique Linux api.

Quoting dnsmasq's author "bind-dynamic (bind individual addresses, keep
up with changes in interface config) ... On linux, there's actually no
sane reason not to use --bind-dynamic, and it's only not the default for
historical reasons."

Let's change history, well on LEDE at least, and change the default!

Signed-off-by: Kevin Darbyshire-Bryant <kevin@darbyshire-bryant.me.uk>