ibmvnic: register netdev after init of adapter

Finish initializing the adapter before registering netdev so state
is consistent.

Fixes: c26eba03 ("ibmvnic: Update reset infrastructure to support tunable parameters")
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>