The Marvell 6390 Ethernet switch family does not perform MDIO
turnaround correctly. Many hardware MDIO bus masters don't care about
this, but the bitbangging implementation in Linux does by default. Add
phy_ignore_ta_mask to the platform data so that the bitbangging code
can be told which devices are known to get TA wrong.

v2
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>