net: phy: don't reschedule state machine when PHY is halted

When being in state PHY_HALTED we don't have to reschedule the
state machine, phy_start() will start it again.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>