ehea: fix operation state report

Currently the ehea driver is missing a call to netif_carrier_off()
before the interface bring-up; this is necessary in order to
initialize the __LINK_STATE_NOCARRIER bit in the net_device state
field. Otherwise, we observe state UNKNOWN on "ip address" command
output.

This patch adds a call to netif_carrier_off() on ehea's net device
open callback.

Reported-by: Xiong Zhou <zhou@redhat.com>
Reference-ID: IBM bz #137702, Red Hat bz #1089134
Signed-off-by: Guilherme G. Piccoli <gpiccoli@linux.vnet.ibm.com>
Signed-off-by: Douglas Miller <dougmill@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>