gve: DQO: Add core netdev features

Add napi netdev device registration, interrupt handling and initial tx
and rx polling stubs. The stubs will be filled in follow-on patches.

Also:
- LRO feature advertisement and handling
- Also update ethtool logic

Signed-off-by: Bailey Forrest <bcf@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Catherine Sullivan <csully@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>