powerpc/fsl: fsl_soc: remove 'fixed-link' parsing code

Parsing and registration of fixed PHY devices was needed with the use of
of_phy_connect_fixed_link() because this function was using the
designated PHY address identifier (first cell of the property) as the
address to bind the PHY on the emulated bus.

Since commit 3be2a49e ("of: provide a
binding for fixed link PHYs") a new pair of functions has been
introduced which allows for dynamic address allocation of these fixed
PHY devices, but also parses the old 'fixed-link' 5-digit property.

Registration of fixed PHY early in platform code was needed because we
could not issue a fixed MDIO bus re-scan within network drivers. The
fixed PHYs had to be registered before the network drivers would call
of_phy_connect_fixed_link(). All of these caveats are solved now, such
that we can safely remove of_add_fixed_phys() now.

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