net: davinci_emac: Restore the internal MDIO accessors return values

net: davinci_emac: Restore the internal MDIO accessors return values

The spatch series converting legacy drivers from miiphy_register to
mdio_register changed the return convention of the davinci_emac internal
MDIO accessors, making the internal code relying on it misbehaving:
no mdiodev get registered and U-Boot crashes when using net cmds in the
context of the old legacy net API.

ATM davinci_emac_initialize and cpu_eth_init don't return a proper value
in that case but fixing them would not avoid the crash.

This change is just a follow-up to the spatch pass, the MDIO accessors
of the mdiodev introduced by the spatch pass retain their proper values.

Signed-off-by: Karl Beldan <karl.beldan+oss@gmail.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>