net: phy: clear phydev->suspended after soft reset

If a soft reset is triggered whilst PHY is in power-down, then
phydev->suspended will remain set. Seems we didn't face any issue yet
caused by this, but better reset the suspended flag after soft reset.

See also the following from 22.2.4.1.1
Resetting a PHY is accomplished by setting bit 0.15 to a logic one.
This action shall set the status and control registers to their default
states.

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