ibmvnic: Set state UP

State is initially reported as UNKNOWN. Before register call
netif_carrier_off(). Once the device is opened, call netif_carrier_on() in
order to set the state to UP.

Signed-off-by: Mick Tarsel <mjtarsel@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>