Register MII_SPEED periodically set to 0 (who is it?)

[DI BACCO ANTONIO - technolabs]

I had to add a setting of mii_speed register of MPC880  in mdio_read and
mdio_write of mii-fec.c because it was periodically set to 0.
My fs_enet is bind to a Virtual PHY and I don't understand who touches
this register.
 
Bye,
Antonio.