phy: Elimination the forced speed reduction algorithm.

In case of fixed speed set up for a NIC (e.g. ethtool -s eth0 autoneg off speed
100 duplex full) with an ethernet cable plugged off, the mentioned algorithm
slows down a NIC speed, so further cable hook-up leads to nonoperable link state.

Signed-off-by: Kirill Kapranov <kapranoff@inbox.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>