AR8031/AR8033 have different status registers for copper
and fiber operation. However, the extended status register
is the same for both operation modes.
As a result of that, ESTATUS_1000_XFULL is set to 1 even when
operating in copper TP mode.
Remove this mode from the supported link modes, as this driver
currently only supports copper operation.
Signed-off-by: David Bauer <mail@david-bauer.net>