ionic: start watchdog after all is setup

The watchdog expects the lif to fully exist when it goes off,
so lets not start the watchdog until all is ready in case there
is some quirky time dialation that makes probe take multiple
seconds.

Fixes: 089406bc ("ionic: add a watchdog timer to monitor heartbeat")
Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>