MIPS: OCTEON: don't lie about interface type of CN3005 board

The fixed-link node in the DT should now take care of the link status,
so this hack can be deleted.

Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org