click.cc: Probe the network devices at init time

click.cc: Probe the network devices at init time

In the early init step, probe the network device if it was not already
probed or configured.

Whithout this step, the `uk_netdev_configure` call will fail, since it
expects the device state to be `UK_NETDEV_UNCONFIGURED`, not
`UK_NETDEV_UNPROBED`.

Signed-off-by: Stefan Jumarea <stefanjumarea02@gmail.com>
Reviewed-by: Razvan Deaconescu <razvand@unikraft.io>
Approved-by: Razvan Deaconescu <razvand@unikraft.io>
Tested-by: Unikraft CI <monkey@unikraft.io>
GitHub-Closes: #7