eea: introduce callback for ndo_get_stats64 and register netdev

eea: introduce callback for ndo_get_stats64 and register netdev

This commit adds support for ndo_get_stats64 to provide accurate
interface statistics. With the TX and RX data paths now fully functional,
it is appropriate to register the netdevice and expose the interface to
userspace.

Registered the network device via register_netdev, and updated the
corresponding unregister_netdev and dev_close routines to ensure
synchronization.

Reviewed-by: Dust Li <dust.li@linux.alibaba.com>
Reviewed-by: Philo Lu <lulie@linux.alibaba.com>
Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Link: https://patch.msgid.link/20260514095138.80680-9-xuanzhuo@linux.alibaba.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>