phylib: Work around bug in Teranetics PHY

The Teranetics PHY does not properly report the link state
for fiber connections. The new PHY code actually checked the link,
and so the FM driver would refuse to talk over a linkless PHY.

But the link may actually be up, so now we always report it as up
for fiber connections on the tn2020.

Signed-off-by: Andy Fleming <afleming@freescale.com>