Updates to sync with upstream changes
- Polling API for EthernetInterface has changed. See https://github.com/m-labs/smoltcp/commit/3868dcdb148ecd30015e1d99283099b171df76c5.
-
proto-ipv4
is now needed to enable IPv4 support. See https://github.com/m-labs/smoltcp/commit/507d2fe0ea390ec309d2e900a9d0d4a70a3dfa3c.