ucc_geth: Intialize link state to down before register_netdev

ucc_geth was indicating link up after a port is administratively enabled even
when nothing is plugged in.  This causes user-space tools to see a spurious link
up the first time after boot.

Signed-off-by: Cliff Clark <cliff_clark@selinc.com>
Signed-off-by: David S. Miller <davem@davemloft.net>