net/fec: carrier off initially to avoid root mount failure

with hardware slow in negotiation, the system did freeze
while trying to mount root on nfs at boot time.

the link state has not been initialised so network stack
tried to start transmission right away. this caused instant
retries, as the driver solely stated business upon link down,
rendering the system unusable.

notify carrier off initially to prevent transmission until
phylib will report link up.

Signed-off-by: Oskar Schirmer <oskar@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>