kernel: distro.config: enable debug friendly USB network adpater

The DB410c has no built in Ethernet, so let's make sure that we can at least get
USB/Ether adaptors to work without any modules.

Signed-off-by: Nicolas Dechesne <nicolas.dechesne@linaro.org>
Signed-off-by: Ondrej Kubik <ondrej.kubik@canonical.com>