There is no point in using a DT property to trigger setting the PSGMII
PHY AZ transmitting ability.
Especially since EEE can be disabled using ethtool anyway.
Fixup the mask for setting the workaround as only BIT(0) is actually being
changed and use the phy_clear_bits_mmd helper instead of reading, then
clearing the bit and writing back as it does everything for us.
Signed-off-by: Robert Marko <robert.marko@sartura.hr>
