If CONFIG_OF is not set, make of_mdiobus_register() call
mdiobus_register() instead of returning -ENOSYS.

This way, we can just call of_mdiobus_register() from all DT-enabled
drivers to handle the compat cases.
Signed-off-by: NDaniel Mack <zonque@gmail.com>
Suggested-by: NFlorian Fainelli <f.fainelli@gmail.com>
Acked-by: NFlorian Fainelli <f.fainelli@gmail.com>
Acked-by: NMugunthan V N <mugunthanvnm@ti.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>