ionic: decouple link message from netdev state

Rearrange the link_up/link_down messages so that we announce
link up when we first notice that the link is up when the
driver loads, and decouple the link_up/link_down messages from
the UP and DOWN netdev state.

Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>